Microscale and Millimeter Scale Devices Including Threaded Elements, Methods for Designing, and Methods for Making

ABSTRACT

Embodiments of the invention provide threaded elements alone, in mating pairs, or in conjunction with other elements. Embodiments of the invention also provide for design and fabrication of such threaded elements without violating minimum feature size design rules or causing other interference issues that may result from the fabrication of such thread elements using a multi-layer multi-material electrochemical fabrication process.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/651,318 (Microfabrica Docket No. P-US283-A-MF), filed on Dec. 31,2009, now abandoned. The '318 application claims benefit of U.S.Provisional Patent Application No. 61/142,135 (Microfabrica Docket No.P-US247-A-MF), filed Dec. 31, 2008, now expired. The referencedapplications are incorporated herein by reference as if set forth infull herein.

FIELD OF THE INVENTION

The present invention relates generally to the field of micro-scale andmillimeter-scale structures and devices and more particularly to suchdevices or structure that include threaded elements that are fabricatedfrom a plurality of adhered layers, designs for such devices, andmulti-material, multi-layer electrochemical fabrication methods forproducing such devices.

BACKGROUND OF THE INVENTION; Electrochemical Fabrication;

An electrochemical fabrication technique for forming three-dimensionalstructures from a plurality of adhered layers is being commerciallypursued by Microfabrica® Inc. (formerly MEMGen Corporation) of Van Nuys,Calif. under the name EFAB®.

Various electrochemical fabrication techniques were described in U.S.Pat. No. 6,027,630, issued on Feb. 22, 2000 to Adam Cohen. Someembodiments of this electrochemical fabrication technique allows theselective deposition of a material using a mask that includes apatterned conformable material on a support structure that isindependent of the substrate onto which plating will occur. Whendesiring to perform an electrodeposition using the mask, the conformableportion of the mask is brought into contact with a substrate, but notadhered or bonded to the substrate, while in the presence of a platingsolution such that the contact of the conformable portion of the mask tothe substrate inhibits deposition at selected locations. Forconvenience, these masks might be generically called conformable contactmasks; the masking technique may be generically called a conformablecontact mask plating process. More specifically, in the terminology ofMicrofabrica Inc. such masks have come to be known as INSTANT MASKS™ andthe process known as INSTANT MASKING™ or INSTANT MASK™ plating.Selective depositions using conformable contact mask plating may be usedto form single selective deposits of material or may be used in aprocess to form multi-layer structures. The teachings of the '630 patentare hereby incorporated herein by reference as if set forth in fullherein. Since the filing of the patent application that led to the abovenoted patent, various papers about conformable contact mask plating(i.e. INSTANT MASKING) and electrochemical fabrication have beenpublished:

-   -   (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Batch production of functional, fully-dense metal        parts with micro-scale features”, Proc. 9th Solid Freeform        Fabrication, The University of Texas at Austin, p161, August        1998.    -   (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High        Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro        Mechanical Systems Workshop, IEEE, p244, January 1999.    -   (3) A. Cohen, “3-D Micromachining by Electrochemical        Fabrication”, Micromachine Devices, March 1999.    -   (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.        Will, “EFAB: Rapid Desktop Manufacturing of True 3-D        Microstructures”, Proc. 2nd International Conference on        Integrated MicroNanotechnology for Space Applications, The        Aerospace Co., April 1999.    -   (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, 3rd        International Workshop on High Aspect Ratio MicroStructure        Technology (HARMST'99), June 1999.    -   (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.        Will, “EFAB: Low-Cost, Automated Electrochemical Batch        Fabrication of Arbitrary 3-D Microstructures”, Micromachining        and Microfabrication Process Technology, SPIE 1999 Symposium on        Micromachining and Microfabrication, September 1999.    -   (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, MEMS        Symposium, ASME 1999 International Mechanical Engineering        Congress and Exposition, November, 1999.    -   (8) A. Cohen, “Electrochemical Fabrication (EFAB™)”, Chapter 19        of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press,        2002.    -   (9) Microfabrication—Rapid Prototyping's Killer Application”,        pages 1-5 of the Rapid Prototyping Report, CAD/CAM Publishing,        Inc., June 1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

An electrochemical deposition for forming multilayer structures may becarried out in a number of different ways as set forth in the abovepatent and publications. In one form, this process involves theexecution of three separate operations during the formation of eachlayer of the structure that is to be formed:

-   -   1. Selectively depositing at least one material by        electrodeposition upon one or more desired regions of a        substrate. Typically this material is either a structural        material or a sacrificial material.    -   2. Then, blanket depositing at least one additional material by        electrodeposition so that the additional deposit covers both the        regions that were previously selectively deposited onto, and the        regions of the substrate that did not receive any previously        applied selective depositions. Typically this material is the        other of a structural material or a sacrificial material.    -   3. Finally, planarizing the materials deposited during the first        and second operations to produce a smoothed surface of a first        layer of desired thickness having at least one region containing        the at least one material and at least one region containing at        least the one additional material.

After formation of the first layer, one or more additional layers may beformed adjacent to an immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed. The removed material is a sacrificialmaterial while the material that forms part of the desired structure isa structural material.

The preferred method of performing the selective electrodepositioninvolved in the first operation is by conformable contact mask plating.In this type of plating, one or more conformable contact (CC) masks arefirst formed. The CC masks include a support structure onto which apatterned conformable dielectric material is adhered or formed. Theconformable material for each mask is shaped in accordance with aparticular cross-section of material to be plated (the pattern ofconformable material is complementary to the pattern of material to bedeposited). At least one CC mask is used for each unique cross-sectionalpattern that is to be plated.

The support for a CC mask is typically a plate-like structure formed ofa metal that is to be selectively electroplated and from which materialto be plated will be dissolved. In this typical approach, the supportwill act as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for multiple CC masks toshare a common support, i.e. the patterns of conformable dielectricmaterial for plating multiple layers of material may be located indifferent areas of a single support structure. When a single supportstructure contains multiple plating patterns, the entire structure isreferred to as the CC mask while the individual plating masks may bereferred to as “submasks”. In the present application such a distinctionwill be made only when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of (1) thesubstrate, (2) a previously formed layer, or (3) a previously depositedportion of a layer on which deposition is to occur. The pressingtogether of the CC mask and relevant substrate occur in such a way thatall openings, in the conformable portions of the CC mask contain platingsolution. The conformable material of the CC mask that contacts thesubstrate acts as a barrier to electrodeposition while the openings inthe CC mask that are filled with electroplating solution act as pathwaysfor transferring material from an anode (e.g. the CC mask support) tothe non-contacted portions of the substrate (which act as a cathodeduring the plating operation) when an appropriate potential and/orcurrent are supplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1A-1C.FIG. 1A shows a side view of a CC mask 8 consisting of a conformable ordeformable (e.g. elastomeric) insulator 10 patterned on an anode 12. Theanode has two functions. One is as a supporting material for thepatterned insulator 10 to maintain its integrity and alignment since thepattern may be topologically complex (e.g., involving isolated “islands”of insulator material). The other function is as an anode for theelectroplating operation. FIG. 1A also depicts a substrate 6, separatedfrom mask 8, onto which material will be deposited during the process offorming a layer. CC mask plating selectively deposits material 22 ontosubstrate 6 by simply pressing the insulator against the substrate thenelectrodepositing material through apertures 26 a and 26 b in theinsulator as shown in FIG. 1B. After deposition, the CC mask isseparated, preferably non-destructively, from the substrate 6 as shownin FIG. 10.

The CC mask plating process is distinct from a “through-mask” platingprocess in that in a through-mask plating process the separation of themasking material from the substrate would occur destructively.Furthermore in a through mask plating process, opening in the maskingmaterial are typically formed while the masking material is in contactwith and adhered to the substrate. As with through-mask plating, CC maskplating deposits material selectively and simultaneously over the entirelayer. The plated region may consist of one or more isolated platingregions where these isolated plating regions may belong to a singlestructure that is being formed or may belong to multiple structures thatare being formed simultaneously. In CC mask plating as individual masksare not intentionally destroyed in the removal process, they may beusable in multiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS.1D-1G. FIG. 1D shows an anode 12′ separated from a mask 8′ that includesa patterned conformable material 10′ and a support structure 20. FIG. 1Dalso depicts substrate 6 separated from the mask 8′. FIG. 1E illustratesthe mask 8′ being brought into contact with the substrate 6. FIG. 1Fillustrates the deposit 22′ that results from conducting a current fromthe anode 12′ to the substrate 6. FIG. 1G illustrates the deposit 22′ onsubstrate 6 after separation from mask 8′. In this example, anappropriate electrolyte is located between the substrate 6 and the anode12′ and a current of ions coming from one or both of the solution andthe anode are conducted through the opening in the mask to the substratewhere material is deposited. This type of mask may be referred to as ananodeless INSTANT MASK™ (AIM) or as an anodeless conformable contact(ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the substrate on which plating is tooccur (e.g. separate from a three-dimensional (3D) structure that isbeing formed). CC masks may be formed in a variety of ways, for example,using a photolithographic process. All masks can be generatedsimultaneously, e.g. prior to structure fabrication rather than duringit. This separation makes possible a simple, low-cost, automated,self-contained, and internally-clean “desktop factory” that can beinstalled almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2A-2F. These figures show that the process involvesdeposition of a first material 2 which is a sacrificial material and asecond material 4 which is a structural material. The CC mask 8, in thisexample, includes a patterned conformable material (e.g. an elastomericdielectric material) 10 and a support 12 which is made from depositionmaterial 2. The conformal portion of the CC mask is pressed againstsubstrate 6 with a plating solution 14 located within the openings 16 inthe conformable material 10. An electric current, from power supply 18,is then passed through the plating solution 14 via (a) support 12 whichdoubles as an anode and (b) substrate 6 which doubles as a cathode. FIG.2A illustrates that the passing of current causes material 2 within theplating solution and material 2 from the anode 12 to be selectivelytransferred to and plated on the substrate 6. After electroplating thefirst deposition material 2 onto the substrate 6 using CC mask 8, the CCmask 8 is removed as shown in FIG. 2B. FIG. 2C depicts the seconddeposition material 4 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 2 as well as over the other portions of thesubstrate 6. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate6. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2D. After repetition of thisprocess for all layers, the multi-layer structure 20 formed of thesecond material 4 (i.e. structural material) is embedded in firstmaterial 2 (i.e. sacrificial material) as shown in FIG. 2E. The embeddedstructure is etched to yield the desired device, i.e. structure 20, asshown in FIG. 2F.

Various components of an exemplary manual electrochemical fabricationsystem 32 are shown in FIGS. 3A-3C. The system 32 consists of severalsubsystems 34, 36, 38, and 40. The substrate holding subsystem 34 isdepicted in the upper portions of each of FIGS. 3A-3C and includesseveral components: (1) a carrier 48, (2) a metal substrate 6 onto whichthe layers are deposited, and (3) a linear slide 42 capable of movingthe substrate 6 up and down relative to the carrier 48 in response todrive force from actuator 44. Subsystem 34 also includes an indicator 46for measuring differences in vertical position of the substrate whichmay be used in setting or determining layer thicknesses and/ordeposition thicknesses. The subsystem 34 further includes feet 68 forcarrier 48 which can be precisely mounted on subsystem 36.

The CC mask subsystem 36 shown in the lower portion of FIG. 3A includesseveral components: (1) a CC mask 8 that is actually made up of a numberof CC masks (i.e. submasks) that share a common support/anode 12, (2)precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on whichthe feet 68 of subsystem 34 can mount, and (5) a tank 58 for containingthe electrolyte 16. Subsystems 34 and 36 also include appropriateelectrical connections (not shown) for connecting to an appropriatepower source (not shown) for driving the CC masking process.

The blanket deposition subsystem 38 is shown in the lower portion ofFIG. 3B and includes several components: (1) an anode 62, (2) anelectrolyte tank 64 for holding plating solution 66, and (3) frame 74 onwhich feet 68 of subsystem 34 may sit. Subsystem 38 also includesappropriate electrical connections (not shown) for connecting the anodeto an appropriate power supply (not shown) for driving the blanketdeposition process.

The planarization subsystem 40 is shown in the lower portion of FIG. 3Cand includes a lapping plate 52 and associated motion and controlsystems (not shown) for planarizing the depositions.

In addition to teaching the use of CC masks for electrodepositionpurposes, the '630 patent also teaches that the CC masks may be placedagainst a substrate with the polarity of the voltage reversed andmaterial may thereby be selectively removed from the substrate. Itindicates that such removal processes can be used to selectively etch,engrave, and polish a substrate, e.g., a plaque.

The '630 patent further indicates that the electroplating methods andarticles disclosed therein allow fabrication of devices from thin layersof materials such as, e.g., metals, polymers, ceramics, andsemiconductor materials. It further indicates that although theelectroplating embodiments described therein have been described withrespect to the use of two metals, a variety of materials, e.g.,polymers, ceramics and semiconductor materials, and any number of metalscan be deposited either by the electroplating methods therein, or inseparate processes that occur throughout the electroplating method. Itindicates that a thin plating base can be deposited, e.g., bysputtering, over a deposit that is insufficiently conductive (e.g., aninsulating layer) so as to enable subsequent electroplating. It alsoindicates that multiple support materials (i.e. sacrificial materials)can be included in the electroplated element allowing selective removalof the support materials.

The '630 patent additionally teaches that the electroplating methodsdisclosed therein can be used to manufacture elements having complexmicrostructure and close tolerances between parts. An example is givenwith the aid of FIGS. 14A-14E of that patent. In the example, elementshaving parts that fit with close tolerances, e.g., having gaps betweenabout 1-5 um, including electroplating the parts of the device in anunassembled, preferably pre-aligned, state and once fabricated. In suchembodiments, the individual parts can be moved into operational relationwith each other or they can simply fall together. Once together theseparate parts may be retained by clips or the like.

Another method for forming microstructures from electroplated metals(i.e. using electrochemical fabrication techniques) is taught in U.S.Pat. No. 5,190,637 to Henry Guckel, entitled “Formation ofMicrostructures by Multiple Level Deep X-ray Lithography withSacrificial Metal layers”. This patent teaches the formation of metalstructure utilizing through mask exposures. A first layer of a primarymetal is electroplated onto an exposed plating base to fill a void in aphotoresist (the photoresist forming a through mask having a desiredpattern of openings), the photoresist is then removed and a secondarymetal is electroplated over the first layer and over the plating base.The exposed surface of the secondary metal is then machined down to aheight which exposes the first metal to produce a flat uniform surfaceextending across both the primary and secondary metals. Formation of asecond layer may then begin by applying a photoresist over the firstlayer and patterning it (i.e. to form a second through mask) and thenrepeating the process that was used to produce the first layer toproduce a second layer of desired configuration. The process is repeateduntil the entire structure is formed and the secondary metal is removedby etching. The photoresist is formed over the plating base or previouslayer by casting and patterning of the photoresist (i.e. voids formed inthe photoresist) are formed by exposure of the photoresist through apatterned mask via X-rays or UV radiation and development of the exposedor unexposed areas.

The '637 patent teaches the locating of a plating base onto a substratein preparation for electroplating materials onto the substrate. Theplating base is indicated as typically involving the use of a sputteredfilm of an adhesive metal, such as chromium or titanium, and then asputtered film of the metal that is to be plated. It is also taught thatthe plating base may be applied over an initial layer of sacrificialmaterial (i.e. a layer or coating of a single material) on the substrateso that the structure and substrate may be detached if desired. In suchcases after formation of the structure the sacrificial material formingpart of each layer of the structure may be removed along the initialsacrificial layer to free the structure. Substrate materials mentionedin the '637 patent include silicon, glass, metals, and silicon withprotected semiconductor devices. A specific example of a plating baseincludes about 150 angstroms of titanium and about 300 angstroms ofnickel, both of which are sputtered at a temperature of 160° C. Inanother example it is indicated that the plating base may consist of 150angstroms of titanium and 150 angstroms of nickel where both are appliedby sputtering.

Electrochemical Fabrication provides the ability to form prototypes andcommercial quantities of miniature objects, parts, structures, devices,and the like at reasonable costs and in reasonable times. In fact,Electrochemical Fabrication is an enabler for the formation of manystructures that were hitherto impossible to produce. ElectrochemicalFabrication opens the spectrum for new designs and products in manyindustrial fields. Even though Electrochemical Fabrication offers thisnew capability and it is understood that Electrochemical Fabricationtechniques can be combined with designs and structures known withinvarious fields to produce new structures, certain uses forElectrochemical Fabrication provide designs, structures, capabilitiesand/or features not known or obvious in view of the state of the art.

A need exists in various fields for miniature devices having improvedcharacteristics, reduced fabrication times, reduced fabrication costs,simplified fabrication processes, greater versatility in device design,improved selection of materials, improved material properties, more costeffective and less risky production of such devices, and/or moreindependence between geometric configuration and the selectedfabrication process.

SUMMARY OF THE INVENTION

It is an object of some embodiments of the invention to provide improveddesign methods for creating threaded elements and fabricating suchelements from a plurality of adhered layers without violating minimumfeature size fabrication rules.

It is an object of some embodiments of the invention to provide improvedthreaded elements for fabrication from a plurality of adhered layerswhere the elements have features removed from regions where minimumfeature size violations might otherwise occur.

It is an object of some embodiments of the invention to provide improvedthreaded elements and threaded element designs having extended axiallengths in regions where the radial dimensions perpendicular to the axisof the threaded device are transitioning from decreasing to increasingdimensions.

It is an object of some embodiments of the invention to providemillimeter-scale and micro-scale threaded devices having unique featuresthat improve one or both of manufacturability and/or devicefunctionality.

Other objects and advantages of various embodiments of the inventionwill be apparent to those of skill in the art upon review of theteachings herein. The various embodiments of the invention, set forthexplicitly herein or otherwise ascertained from the teachings herein,may address one or more of the above objects alone or in combination, oralternatively may address some other object ascertained from theteachings herein. It is not necessarily intended that all objects beaddressed by any single aspect of the invention even though that may bethe case with regard to some aspects.

A first aspect of the invention provides a method for designing amicro-scale or millimeter scale threaded element, for fabrication from aplurality of planar multi-material layers, wherein each layer is formedfrom at least one structural material and at least one sacrificialmaterial, including: (a) creating a solid model representing the desiredthreaded element; (b) cutting the solid model along selected planescorresponding to layers from which the element will be fabricated; (c)identifying features of the individual layers that violate minimumfeature size rules; and (d) removing at least a portion of the featuresfrom the design that violate minimum feature size rules to derive amodified element design.

A second aspect of the invention provides a method for designing amicro-scale or millimeter scale threaded element, for fabrication from aplurality of planar multi-material layers, wherein each layer is formedfrom at least one structural material and at least one sacrificialmaterial, including: (a) creating a solid model representing acomplement of the desired threaded element; (b) cutting the solid modelalong selected planes corresponding to layers from which the elementwill be fabricated; (c) identifying features of the individual layersthat violate minimum feature size rules; and (d) removing at least aportion of the features from the design that violate minimum featuresize rules to derive a modified complementary element design.

A third aspect of the invention provides a method for fabricating amicro-scale or millimeter scale threaded element from a plurality ofplanar multi-material layers, wherein each layer is formed from at leastone structural material and at least one sacrificial material,including: (a) creating a solid model representing the desired threadedelement; (b) cutting the solid model along selected planes correspondingto layers from which the element will be fabricated, (c) identifyingfeatures of the individual layers that violate minimum feature sizerules; (d) removing at least a portion of the features from the designthat violate minimum feature size rules to derive a modified elementdesign; (e) using the modified element design to create datarepresenting each layer of the element; (f) supplying a substrate onwhich to fabricate a first multi-material layer of the element; (g)fabricating the first multi-material layer on the substrate; (h)fabricating a plurality of successive layers with each formed on apreviously formed layer; and (i) after fabrication of the plurality oflayers, separating the sacrificial material from multiple layers ofstructural material.

A fourth aspect of the invention provides a method for designing amicro-scale or millimeter scale threaded element, for fabrication from aplurality of planar multi-material layers, wherein each layer is formedfrom at least one structural material and at least one sacrificialmaterial, including: (a) creating a solid model representing acomplement of the desired threaded element; (b) cutting the solid modelalong selected planes corresponding to layers from which the elementwill be fabricated, (c) identifying features of the individual layersthat violate minimum feature size rules; and (d) removing at least aportion of the features from the design that violate minimum featuresize rules to derive a modified complementary element design; (e) usingthe modified complementary element design to create data representingeach layer of the element; (f) supplying a substrate on which tofabricate a first multi-material layer of the element; (g) fabricatingthe first multi-material layer on the substrate; (h) fabricating aplurality of successive layers with each formed on a previously formedlayer; and (i) after fabrication of the plurality of layers, separatingthe sacrificial material from multiple layers of structural material.

Numerous variations of all of the four aspects of the invention existand include, for example, wherein one or more of the followingconditions are met: (1) the threaded element is formed using amulti-material multi-layer electrochemical fabrication process, (2) thethreaded structure is released from a build substrate after fabrication,(3) the threaded element is used with a another threaded element that isformed from a plurality of adhered layers; (4) the threaded element isused with another threaded element formed in a non-layered manner; (5)the threaded element has a thread with a design pitch (turns/mm) whereinthe layers from which the element is formed have thickness (mm) andwherein the ratio of pitch to layer thickness that is greater than 1:5;(6) the threaded element has a thread with a design pitch (turns/mm)wherein the layers from which the element is formed have thickness (mm)and wherein the ratio of layer pitch to layer thickness is an integergreater than 4, more preferably greater than 6, and even more preferablygreater than 8; and/or; (7) The thread element is co-fabricated with oneor more elements intended to provide one or more of (a) features toenhance tapping; (b) spring biasing, (c) preloading, (d) eased handling;(e) locking once engaged, and/or (f) release once/curved/tapered screws;variable pitch/diameter screws; built-in springs and washers.

A fifth aspect provides a method for fabricating a micro-scale ormillimeter scale male threaded element from a plurality of planarmulti-material layers, wherein each layer is formed from at least onestructural material and at least one sacrificial material, including:(a) creating a solid model representing the desired male threadedelement cutting the solid model along selected planes corresponding tolayers from which the element will be fabricated, (b) supplying asubstrate on which to fabricate a first multi-material layer of theelement, (c) fabricating the first multi-material layer on thesubstrate, (d) fabricating a plurality of successive layers with eachformed on a previously formed layer; and (e) after fabrication of theplurality of layers, separating the sacrificial material from multiplelayers of structural material to release the male threaded element,wherein the male threaded element has an axial dimension and a radialdimension that extends perpendicular to the axial dimension, the malethreaded element includes at least one outward facing thread comprisingradial extensions and radial depressions that define a spiral turn of atleast 90° around and along the axial dimension, wherein there exists amaximum and minimum radial extension for the thread for each axialposition; and wherein selected portions of the radial features of thethreaded element meet a criteria selected from the group consisting of:(1) the selected portions are located along the maximum radial dimensionand are flattened relative to non-selected portions of the maximumradial dimension such that the selected portions have longer axiallengths relative to the axial length of the non-selected portions, (2)the selected portions are located along the maximum radial dimension andare flattened relative to non-selected portions of the maximum radialdimension such that the selected portions have longer axial lengthsrelative to the axial length of the non-selected portions wherein thelonger axial length is at least as large as the layer thickness, (3) theselected portions are located along the maximum radial dimension and areflattened relative to non-selected portions of the maximum radialdimension such that the selected portions have longer axial lengthsrelative to the axial length of the non-selected portions wherein thelonger axial length is at least as large as a minimum feature size, (4)the selected portions are located along the minimum radial dimensionalong and are flattened relative to non-selected portions of the minimumradial dimension such that the selected portions have longer axiallengths relative to the axial length of the non-selected portions, (5)the selected portions are located along the minimum radial dimensionalong and are flattened relative to non-selected portions of the minimumradial dimension such that the selected portions have longer axiallengths relative to the axial length of the non-selected portionswherein the longer axial length is at least as large as the layerthickness, and (6) the selected portions are located along the minimumradial dimension along and are flattened relative to non-selectedportions of the minimum radial dimension such that the selected portionshave longer axial lengths relative to the axial length of thenon-selected portions wherein the longer axial length is at least aslarge as a minimum feature size.

Numerous variations of the fifth aspect of the invention exist andinclude, for example: (1) the spiral turn being continuous, (2) thespiral turn being discontinuous, (3) the spiral turn extending at least180°, (4) the spiral turn extending at least 360°, (5) the spiral turnextending at least 720°, and (6) the female thread element being formedalong with the male threaded element.

Additional examples of variation (6) of the fifth aspect of theinvention include, for example: (a) the female and male threadedelements being in an at least partially assembled state, and (b) thefemale threaded element including a plurality of release holes.

A sixth aspect of the invention provides a method for fabricating amicro-scale or millimeter scale female threaded element from a pluralityof planar multi-material layers, wherein each layer is formed from atleast one structural material and at least one sacrificial material,including: (a) creating a solid model representing the desired femalethreaded element, (b) cutting the solid model along selected planescorresponding to layers from which the element will be fabricated, (c)supplying a substrate on which to fabricate a first multi-material layerof the element, (d) fabricating the first multi-material layer on thesubstrate, (e) fabricating a plurality of successive layers with eachformed on a previously formed layer; and (f) after fabrication of theplurality of layers, separating the sacrificial material from multiplelayers of structural material to release the female threaded element,wherein the female threaded element has an axial dimension and a radialdimension that extends perpendicular to the axial dimension, wherein thefemale threaded element includes at least one inward facing threadcomprising radial extensions defining openings of smaller radius andradial depressions defining openings of larger radius, wherein thethread provides a spiral turn of at least 90° around and along the axialdimension, wherein there exists a maximum and minimum radial extensionfor the thread for each axial position; and wherein selected portions ofthe radial features of the threaded element meet a criteria selectedfrom the group consisting of: (1) the selected portions are locatedalong the maximum radial dimension and are flattened relative tonon-selected portions of the maximum radial dimension such that theselected portions have longer axial lengths relative to the axial lengthof the non-selected portions, (2) the selected portions are locatedalong the maximum radial dimension and are flattened relative tonon-selected portions of the maximum radial dimension such that theselected portions have longer axial lengths relative to the axial lengthof the non-selected portions wherein the longer axial length is at leastas large as the layer thickness, (3) the selected portions are locatedalong the maximum radial dimension and are flattened relative tonon-selected portions of the maximum radial dimension such that theselected portions have longer axial lengths relative to the axial lengthof the non-selected portions wherein the longer axial length is at leastas large as a minimum feature size, (4) the selected portions arelocated along the minimum radial dimension along and are flattenedrelative to non-selected portions of the minimum radial dimension suchthat the selected portions have longer axial lengths relative to theaxial length of the non-selected portions, (5) the selected portions arelocated along the minimum radial dimension along and are flattenedrelative to non-selected portions of the minimum radial dimension suchthat the selected portions have longer axial lengths relative to theaxial length of the non-selected portions wherein the longer axiallength is at least as large as the layer thickness, and (6) the selectedportions are located along the minimum radial dimension along and areflattened relative to non-selected portions of the minimum radialdimension such that the selected portions have longer axial lengthsrelative to the axial length of the non-selected portions wherein thelonger axial length is at least as large as a minimum feature size.

Numerous variations of the sixth aspect of the invention exist andinclude, for example: (1) the spiral turn being continuous, (2) thespiral turn being discontinuous, (3) the spiral turn extending at least180°, (4) the spiral turn extending at least 360°, (5) the spiral turnextending at least 720°, and (6) the male thread element being formedalong with the female threaded element.

Additional examples of variation (6) of the sixth aspect of theinvention include, for example: the female and male threaded elementsbeing at in an at least partially assembled state during formation; andfurthermore the female threaded element may include a plurality ofrelease holes.

A seventh aspect of the invention provides a micro-scale or millimeterscale male threaded element, including: (a) an axial dimension and aradial dimension that extends perpendicular to the axial dimension, (b)at least one outward facing thread comprising radial extensions andradial depressions that define a spiral turn of at least 90° around andalong the axial dimension, wherein the threaded element has a stairstepped configuration with the stair steps defining a plurality ofplanes spaced from adjacent planes by a layer thickness, wherein thereexists a maximum and minimum radial extension for the thread for eachaxial position; and wherein selected portions of the radial features ofthe threaded element meet a criteria selected from the group consistingof: (1) the selected portions are located along the maximum radialdimension and are flattened relative to non-selected portions of themaximum radial dimension such that the selected portions have longeraxial lengths relative to the axial length of the non-selected portions,(2) the selected portions are located along the maximum radial dimensionand are flattened relative to non-selected portions of the maximumradial dimension such that the selected portions have longer axiallengths relative to the axial length of the non-selected portionswherein the longer axial length is at least as large as the layerthickness, (3) the selected portions are located along the maximumradial dimension and are flattened relative to non-selected portions ofthe maximum radial dimension such that the selected portions have longeraxial lengths relative to the axial length of the non-selected portionswherein the longer axial length is at least as large as a minimumfeature size, (4) the selected portions are located along the minimumradial dimension along and are flattened relative to non-selectedportions of the minimum radial dimension such that the selected portionshave longer axial lengths relative to the axial length of thenon-selected portions, (5) the selected portions are located along theminimum radial dimension along and are flattened relative tonon-selected portions of the minimum radial dimension such that theselected portions have longer axial lengths relative to the axial lengthof the non-selected portions wherein the longer axial length is at leastas large as the layer thickness, and (6) the selected portions arelocated along the minimum radial dimension along and are flattenedrelative to non-selected portions of the minimum radial dimension suchthat the selected portions have longer axial lengths relative to theaxial length of the non-selected portions wherein the longer axiallength is at least as large as a minimum feature size.

Numerous variations of the seventh aspect of the invention exists andinclude: (1) the spiral turn being continuous, (2) the spiral turn beingdiscontinuous, (3) the spiral turn extending at least 180°, (4) thespiral turn extending at least 360°, (5) the spiral turn extending atleast 720°, and (6) the male thread element being configured to threadinto a counterpart female threaded element.

An eighth aspect of the invention provides a micro-scale or millimeterscale female threaded element, including: (a) an axial dimension and aradial dimension that extends perpendicular to the axial dimension, (b)at least one inward facing thread comprising radial extensions definingopenings of smaller radius and radial depressions defining openings oflarger radius, wherein the thread provides a spiral turn of at least 90°around and along the axial dimension, wherein the thread has a stairstepped configuration with the stair steps defining a plurality ofplanes spaced from adjacent planes by a layer thickness, wherein thereexists a maximum and minimum radial extension for the thread for eachaxial position; and wherein selected portions of the radial features ofthe threaded element meet a criteria selected from the group consistingof: (1) the selected portions are located along the maximum radialdimension and are flattened relative to non-selected portions of themaximum radial dimension such that the selected portions have longeraxial lengths relative to the axial length of the non-selected portions,(2) the selected portions are located along the maximum radial dimensionand are flattened relative to non-selected portions of the maximumradial dimension such that the selected portions have longer axiallengths relative to the axial length of the non-selected portionswherein the longer axial length is at least as large as the layerthickness, (3) the selected portions are located along the maximumradial dimension and are flattened relative to non-selected portions ofthe maximum radial dimension such that the selected portions have longeraxial lengths relative to the axial length of the non-selected portionswherein the longer axial length is at least as large as a minimumfeature size, (4) the selected portions are located along the minimumradial dimension along and are flattened relative to non-selectedportions of the minimum radial dimension such that the selected portionshave longer axial lengths relative to the axial length of thenon-selected portions, (5) the selected portions are located along theminimum radial dimension along and are flattened relative tonon-selected portions of the minimum radial dimension such that theselected portions have longer axial lengths relative to the axial lengthof the non-selected portions wherein the longer axial length is at leastas large as the layer thickness, and (6) the selected portions arelocated along the minimum radial dimension along and are flattenedrelative to non-selected portions of the minimum radial dimension suchthat the selected portions have longer axial lengths relative to theaxial length of the non-selected portions wherein the longer axiallength is at least as large as a minimum feature size.

Numerous variations of the eighth aspect of the invention exist andinclude, for example: (1) the spiral turn being continuous, (2) thespiral turn being discontinuous, (3) the spiral turn extending at least180°, (4) the spiral turn extending at least 360°, (5) the spiral turnextending at least 720°, and (6) the female thread element beingconfigured to receive a counterpart male threaded element.

A ninth aspect of the invention provides a micro-scale or millimeterscale device, including: (a) a male threaded element, including (i) anaxial dimension and a radial dimension that extends perpendicular to theaxial dimension, (ii) at least one outward facing thread comprisingradial extensions and radial depressions that define a spiral turn of atleast 90° around and along the axial dimension, wherein the malethreaded element has a stair stepped configuration with the stair stepsdefining a plurality of planes spaced from adjacent planes by a layerthickness, and (b) a female threaded element, including: (i) an axialdimension and a radial dimension that extends perpendicular to the axialdimension, at least one inward facing female thread comprising radialextensions defining openings of smaller radius and radial depressionsdefining openings of larger radius, wherein the thread provides a spiralturn of at least 90° around and along the axial dimension, wherein thefemale threaded element has a stair stepped configuration with the stairsteps defining a plurality of planes spaced from adjacent planes by alayer thickness, wherein the male threaded element is configured tothread into the female threaded element.

Numerous variations of the ninth aspect of the invention exist andinclude, for example: (1) the spiral turn of the male threaded elementbeing continuous, (2) the spiral turn of the male threaded element beingdiscontinuous, (3) the spiral turn of both the male and female threadedelements extending at least 180°, (4) the spiral turn of both the maleand female threaded elements extending at least 360°, (5) the spiralturn of both the male and female threaded elements extending at least720°, (6) the female threaded element including a plurality of releaseholes, (7) the male threaded element including a coreless thread, (8)the male threaded element including a helix without a central core, and(9) the male threaded element including a multiple threaded element.

An additional example of variation (1) of the ninth aspect of theinvention includes the spiral turn of the female threaded element beingcontinuous. A further example of variation (1) of the ninth aspect ofthe invention includes the spiral turn of the female threaded elementbeing discontinuous.

An additional example of variation (2) of the ninth aspect of theinvention includes the spiral turn of the female threaded element beingcontinuous. A further example of variation (2) of the ninth aspect ofthe invention includes the spiral turn of the female threaded elementbeing discontinuous.

A tenth aspect of the invention provides a micro-scale or millimeterscale device that includes: comprising: (a) a threaded male element thatincludes: (i) a longitudinal axis; (ii) a stair stepped configurationwith the stair steps defining a plurality of planes spaced from adjacentplanes by a layer thickness; (iii) for a majority of the length of thethreaded element each position along the longitudinal axis has at leastone minimum and at least one maximum radial extension, wherein themaximum radial extension that has a surface with a perpendicularcomponent that faces away from the longitudinal axis and the minimumradial extension has a surface with a perpendicular component that facestoward the longitudinal axis.

Numerous variations of the tenth aspect of the invention are possibleand include, for example: (1) the threaded element additionallyextending for a plurality of complete rotations (e.g. two turns to tenturns); (2) at least a portion of the maximum radial extensions haveaxial lengths greater than the layer thickness; (3) the deviceadditionally includes a threaded female receptacle that rotationallyengages at least a portion of the threaded male element; (4) thethreaded male element ends in a head element at one end which includesan surface for engaging a tool to cause relative turning of the threadelement.

The disclosure of the present invention provides for the design ofthreaded elements, including providing design modifications to avoidviolating minimum features size rules and/or other structuralinterference issues, and fabrication of such elements from a pluralityof adhered layers wherein each successive layer comprising at least twomaterials, one of which is a structural material and the other of whichis a sacrificial material, and wherein each successive layer defines asuccessive cross-section of the three-dimensional structure, and whereinthe forming of each of the plurality of successive layers includes: (i)depositing a first of the at least two materials, (ii) depositing asecond of the at least two materials, (iii) the planarization of thefirst and second materials; and after the forming of the plurality ofsuccessive layers, separating at least a portion of the sacrificialmaterial from the structural material to reveal the three-dimensionalstructure.

Other aspects of the invention will be understood by those of skill inthe art upon review of the teachings herein. Other aspects of theinvention may involve combinations of the above noted aspects of theinvention or of their variations. These other aspects of the inventionmay provide various combinations of the aspects and variations presentedabove as well as provide other configurations, structures, functionalrelationships, and processes that have not been specifically set forthabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C schematically depict side views of various stages of a CCmask plating process, while FIGS. 1D-G schematically depict a side viewsof various stages of a CC mask plating process using a different type ofCC mask.

FIGS. 2A-2F schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3A-3C schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2A-2F.

FIGS. 4A-4F schematically depict the formation of a first layer of astructure using adhered mask plating where the blanket deposition of asecond material overlays both the openings between deposition locationsof a first material and the first material itself

FIG. 4G depicts the completion of formation of the first layer resultingfrom planarizing the deposited materials to a desired level.

FIGS. 4H and 4I respectively depict the state of the process afterformation of the multiple layers of the structure and after release ofthe structure from the sacrificial material.

FIG. 5A-5C provide plan (FIG. 5A), perspective (FIG. 5B), andperspective section (FIG. 5C) views of a solid model of a male threadedstructure or element without modifications that address minimum featuresize limitations or other interference issues as may be necessary whenforming the device from a plurality of adhered layers.

FIGS. 6A-6F provide plan views (FIGS. 6B-6D), perspective views (FIG.6A), and perspective section views (FIGS. 6E-6F) of a solid model of amale threaded structure or element having an axial orientation along theY-axis and design modifications on portions of the maximum radialfeatures and minimum radial features, respectively, to allow formationwithout violating minimum feature size rules.

FIGS. 7A-7E provide a perspective view (FIG. 7A), plan section views(FIGS. 7B & 7D), and perspective section views (FIGS. 7C-7E) views of asolid model of a sample female threaded structure.

FIGS. 8A-8B provide a mated or partially engaged perspective sectionview (FIG. 8B) and a mated or partially engaged perspective view (FIG.8A) view of the male and female threaded structures.

FIGS. 9A-9B provide a perspective view (FIG. 9A) and a perspectivesection view (FIG. 9B) of a layerized male threaded structure with thestacking axis of the layers being parallel to the longitudinal axis ofthe threaded device wherein the threaded device includes spiralingregions of maximum radial extension and minimum radial extension at eachposition along the axial length of the threaded element.

FIGS. 10A-10B provide a perspective view (FIG. 10A) and perspectivesection view (FIG. 10B) of a layerized male threaded structure with thestacking axis of the layers being perpendicular to the longitudinal axisof the threaded device.

FIGS. 11A-11B provide a perspective view (FIG. 11A) and perspectivesection view (FIG. 11B) of a layerized female threaded structure withthe stacking direction of the layers corresponding to the longitudinalaxis of the threaded device.

FIGS. 12A-12B provide a perspective view (FIG. 12A) and a perspectivesection view (FIG. 12B) of a layerized female threaded structure withthe stacking direction of the layers perpendicular to the longitudinalaxis of the threaded device.

FIGS. 13A-13C a provide plan view (FIG. 13A), a perspective view (FIG.13B), and section view (FIG. 13C) of a solid model of a male threadedstructure or element having design modifications that allow formationwithout violating minimum feature size rules, wherein the designmodifications include expanded axial lengths of the threaded element.

FIGS. 14A-14B provide a perspective (FIG. 14A) and perspective sectionview (FIG. 14B) of a solid model of a female threaded structure havingthe design modifications corresponding to those of male threadedstructure of FIGS. 13A and 13B.

FIG. 15A-15C provide a plan view (FIG. 15A), a perspective view (FIG.15B), and a perspective section view (FIG. 15C) of a solid model of amale threaded structure that comes closer to a cork-screw or helicalconfiguration of the device as whole as opposed to only the threadsedges themselves tracing a helical path.

FIG. 15D provides a layerized version of the threaded device of FIGS.15A-15C with a stacking axis perpendicular to the longitudinal axis ofthe thread element.

FIG. 16A-16B provide a perspective view (FIG. 16A) and a perspectivesection view (FIG. 16B) of a solid model of a female male threadedstructure or element corresponding to the male element of FIGS. 15A-15C.

FIG. 17 illustrates a device having holes provided with channels thatmay facilitate release of chips and other fragments produced by thetapping process.

FIG. 18 provides a cut view of example male and female threaded elementshaving common axes where both elements have similar axial lengths fortheir minimum and maximum radial dimensions wherein the elements havecertain radial thread overlap that is dictated by, for example, thethread pitch and the required axial length of the minimum and maximumfeatures.

FIG. 19 provides a cut view of an alternative thread configuration of amale threaded element and a female threaded element that have commonaxes and a thread overlap where the minimum and maximum radial featuresfor the male thread have similar axial lengths, while the minimum andmaximum radial features for the female thread also have similar axiallengths but where the axial lengths of the female features are onlyabout one-half of that of the male features.

FIG. 20 provides a cut view of an alternative thread configuration of amale threaded element and a female threaded element that have commonaxes and a thread overlap where the minimum and maximum radial featuresfor the male thread have different axial lengths while the minimum andmaximum radial features for the female thread also have different axiallengths but where the axial lengths of the minimum radial femalefeatures are less than that of the minimum radial male features and themaximum radial length of the maximum female radial features are greaterthan that of the maximum radial male features.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS ElectrochemicalFabrication in General

FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of one form ofelectrochemical fabrication. Other electrochemical fabricationtechniques are set forth in the '630 patent referenced above, in thevarious previously incorporated publications, in various other patentsand patent applications incorporated herein by reference. Still othersmay be derived from combinations of various approaches described inthese publications, patents, and applications, or are otherwise known orascertainable by those of skill in the art from the teachings set forthherein. All of these techniques may be combined with those of thevarious embodiments of various aspects of the invention to yieldenhanced embodiments. Still other embodiments may be derived fromcombinations of the various embodiments explicitly set forth herein.

FIGS. 4A-4I illustrate various stages in the formation of a single layerof a multi-layer fabrication process where a second metal is depositedon a first metal as well as in openings in the first metal so that thefirst and second metal form part of the layer. In FIG. 4A a side view ofa substrate 82 is shown, onto which patternable photoresist 84 is castas shown in FIG. 4B. In FIG. 4C, a pattern of resist is shown thatresults from the curing, exposing, and developing of the resist. Thepatterning of the photoresist 84 results in openings or apertures92(a)-92(c) extending from a surface 86 of the photoresist through thethickness of the photoresist to surface 88 of the substrate 82. In FIG.4D a metal 94 (e.g. nickel) is shown as having been electroplated intothe openings 92(a)-92(c). In FIG. 4E the photoresist has been removed(i.e. chemically stripped) from the substrate to expose regions of thesubstrate 82 which are not covered with the first metal 94. In FIG. 4F asecond metal 96 (e.g. silver) is shown as having been blanketelectroplated over the entire exposed portions of the substrate 82(which is conductive) and over the first metal 94 (which is alsoconductive). FIG. 4G depicts the completed first layer of the structurewhich has resulted from the planarization of the first and second metalsdown to a height that exposes the first metal and sets a thickness forthe first layer. In FIG. 4H the result of repeating the process stepsshown in FIGS. 4B-4 G several times to form a multi-layer structure areshown where each layer consists of two materials. For most applications,one of these materials is removed as shown in FIG. 4I to yield a desired3-D structure 98 (e.g. component or device).

Various embodiments of various aspects of the invention are directed toformation of three-dimensional structures from materials some of whichmay be electrodeposited or electroless deposited. Some of thesestructures may be formed form a single build level formed from one ormore deposited materials while others are formed from a plurality ofbuild layers each including at least two materials (e.g. two or morelayers, more preferably five or more layers, and most preferably ten ormore layers). In some embodiments, layer thicknesses may be as small asone micron or as large as fifty microns. In other embodiments, thinnerlayers may be used while in other embodiments, thicker layers may beused. In some embodiments structures having features positioned withmicron level precision and minimum features size on the order of tens ofmicrons are to be formed. In other embodiments structures with lessprecise feature placement and/or larger minimum features may be formed.In still other embodiments, higher precision and smaller minimum featuresizes may be desirable. In the present application meso-scale andmillimeter scale have the same meaning and refer to devices that mayhave one or more dimensions extending into the 0.5-20 millimeter range,or somewhat larger and with features positioned with precision in the10-100 micron range and with minimum features sizes on the order of 100microns.

The various embodiments, alternatives, and techniques disclosed hereinmay form multi-layer structures using a single patterning technique onall layers or using different patterning techniques on different layers.For example, various embodiments of the invention may perform selectivepatterning operations using conformable contact masks and maskingoperations (i.e. operations that use masks which are contacted to butnot adhered to a substrate), proximity masks and masking operations(i.e. operations that use masks that at least partially selectivelyshield a substrate by their proximity to the substrate even if contactis not made), non-conformable masks and masking operations (i.e. masksand operations based on masks whose contact surfaces are notsignificantly conformable), and/or adhered masks and masking operations(masks and operations that use masks that are adhered to a substrateonto which selective deposition or etching is to occur as opposed toonly being contacted to it). Conformable contact masks, proximity masks,and non-conformable contact masks share the property that they arepreformed and brought to, or in proximity to, a surface which is to betreated (i.e. the exposed portions of the surface are to be treated).These masks can generally be removed without damaging the mask or thesurface that received treatment to which they were contacted, or locatedin proximity to. Adhered masks are generally formed on the surface to betreated (i.e. the portion of that surface that is to be masked) andbonded to that surface such that they cannot be separated from thatsurface without being completely destroyed damaged beyond any point ofreuse. Adhered masks may be formed in a number of ways including (1) byapplication of a photoresist, selective exposure of the photoresist, andthen development of the photoresist, (2) selective transfer ofpre-patterned masking material, and/or (3) direct formation of masksfrom computer controlled depositions of material.

Patterning operations may be used in selectively depositing materialand/or may be used in the selective etching of material. Selectivelyetched regions may be selectively filled in or filled in via blanketdeposition, or the like, with a different desired material. In someembodiments, the layer-by-layer build up may involve the simultaneousformation of portions of multiple layers. In some embodiments,depositions made in association with some layer levels may result indepositions to regions associated with other layer levels (i.e. regionsthat lie within the top and bottom boundary levels that define adifferent layer's geometric configuration). Such use of selectiveetching and interlaced material deposition in association with multiplelayers is described in U.S. patent application Ser. No. 10/434,519, bySmalley, now U.S. Pat. No. 7,252,861, and entitled “Methods of andApparatus for Electrochemically Fabricating Structures Via InterlacedLayers or Via Selective Etching and Filling of Voids layer elements”which is hereby incorporated herein by reference as if set forth infull.

Temporary substrates on which structures may be formed may be of thesacrificial-type (i.e. destroyed or damaged during separation ofdeposited materials to the extent they cannot be reused),non-sacrificial-type (i.e. not destroyed or excessively damaged, i.e.not damaged to the extent they may not be reused, e.g. with asacrificial or release layer located between the substrate and theinitial layers of a structure that is formed). Non-sacrificialsubstrates may be considered reusable, with little or no rework (e.g.replanarizing one or more selected surfaces or applying a release layer,and the like) though they may or may not be reused for a variety ofreasons.

DEFINITIONS

This section of the specification is intended to set forth definitionsfor a number of specific terms that may be useful in describing thesubject matter of the various embodiments of the invention. It isbelieved that the meanings of most if not all of these terms is clearfrom their general use in the specification but they are set forthhereinafter to remove any ambiguity that may exist. It is intended thatthese definitions be used in understanding the scope and limits of anyclaims that use these specific terms. As far as interpretation of theclaims of this patent disclosure are concerned, it is intended thatthese definitions take presence over any contradictory definitions orallusions found in any materials which are incorporated herein byreference.

“Build” as used herein refers, as a verb, to the process of building adesired structure or plurality of structures from a plurality of appliedor deposited materials which are stacked and adhered upon application ordeposition or, as a noun, to the physical structure or structures formedfrom such a process. Depending on the context in which the term is used,such physical structures may include a desired structure embedded withina sacrificial material or may include only desired physical structureswhich may be separated from one another or may require dicing and/orslicing to cause separation.

“Build axis” or “build orientation” is the axis or orientation that issubstantially perpendicular to substantially planar levels of depositedor applied materials that are used in building up a structure. Theplanar levels of deposited or applied materials may be or may not becompletely planar but are substantially so in that the overall extent oftheir cross-sectional dimensions are significantly greater than theheight of any individual deposit or application of material (e.g. 100,500, 1000, 5000, or more times greater). The planar nature of thedeposited or applied materials may come about from use of a process thatleads to planar deposits or it may result from a planarization process(e.g. a process that includes mechanical abrasion, e.g. lapping, flycutting, grinding, or the like) that is used to remove material regionsof excess height. Unless explicitly noted otherwise, “vertical” as usedherein refers to the build axis or nominal build axis (if the layers arenot stacking with perfect registration) while “horizontal” refers to adirection within the plane of the layers (i.e. the plane that issubstantially perpendicular to the build axis).

“Build layer” or “layer of structure” as used herein does not refer to adeposit of a specific material but instead refers to a region of a buildlocated between a lower boundary level and an upper boundary level whichgenerally defines a single cross-section of a structure being formed orstructures which are being formed in parallel. Depending on the detailsof the actual process used to form the structure, build layers aregenerally formed on and adhered to previously formed build layers. Insome processes the boundaries between build layers are defined byplanarization operations which result in successive build layers beingformed on substantially planar upper surfaces of previously formed buildlayers. In some embodiments, the substantially planar upper surface ofthe preceding build layer may be textured to improve adhesion betweenthe layers. In other build processes, openings may exist in or be formedin the upper surface of a previous but only partially formed buildlayers such that the openings in the previous build layers are filledwith materials deposited in association with current build layers whichwill cause interlacing of build layers and material deposits. Suchinterlacing is described in U.S. patent application Ser. No. 10/434,519now U.S. Pat. No. 7,252,861. This referenced application is incorporatedherein by reference as if set forth in full. In most embodiments, abuild layer includes at least one primary structural material and atleast one primary sacrificial material. However, in some embodiments,two or more primary structural materials may used without a primarysacrificial material (e.g. when one primary structural material is adielectric and the other is a conductive material). In some embodiments,build layers are distinguishable from each other by the source of thedata that is used to yield patterns of the deposits, applications,and/or etchings of material that form the respective build layers. Forexample, data descriptive of a structure to be formed which is derivedfrom data extracted from different vertical levels of a datarepresentation of the structure define different build layers of thestructure. The vertical separation of successive pairs of suchdescriptive data may define the thickness of build layers associatedwith the data. As used herein, at times, “build layer” may be looselyreferred simply as “layer”. In many embodiments, deposition thickness ofprimary structural or sacrificial materials (i.e. the thickness of anyparticular material after it is deposited) is generally greater than thelayer thickness and a net deposit thickness is set via one or moreplanarization processes which may include, for example, mechanicalabrasion (e.g. lapping, fly cutting, polishing, and the like) and/orchemical etching (e.g. using selective or non-selective etchants). Thelower boundary and upper boundary for a build layer may be set anddefined in different ways. From a design point of view they may be setbased on a desired vertical resolution of the structure (which may varywith height). From a data manipulation point of view, the vertical layerboundaries may be defined as the vertical levels at which datadescriptive of the structure is processed or the layer thickness may bedefined as the height separating successive levels of cross-sectionaldata that dictate how the structure will be formed. From a fabricationpoint of view, depending on the exact fabrication process used, theupper and lower layer boundaries may be defined in a variety ofdifferent ways. For example by planarization levels or effectiveplanarization levels (e.g. lapping levels, fly cutting levels, chemicalmechanical polishing levels, mechanical polishing levels, verticalpositions of structural and/or sacrificial materials after relativelyuniform etch back following a mechanical or chemical mechanicalplanarization process). For example, by levels at which process steps oroperations are repeated. At levels at which, at least theoretically,lateral extends of structural material can be changed to define newcross-sectional features of a structure.

“Layer thickness” is the height along the build axis between a lowerboundary of a build layer and an upper boundary of that build layer.

“Planarization” is a process that tends to remove materials, above adesired plane, in a substantially non-selective manner such that alldeposited materials are brought to a substantially common height ordesired level (e.g. within 20%, 10%, 5%, or even 1% of a desired layerboundary level). For example, lapping removes material in asubstantially non-selective manner though some amount of recession onematerial or another may occur (e.g. copper may recess relative tonickel). Planarization may occur primarily via mechanical means, e.g.lapping, grinding, fly cutting, milling, sanding, abrasive polishing,frictionally induced melting, other machining operations, or the like(i.e. mechanical planarization). Mechanical planarization maybe followedor proceeded by thermally induced planarization (.e.g. melting) orchemically induced planarization (e.g. etching). Planarization may occurprimarily via a chemical and/or electrical means (e.g. chemical etching,electrochemical etching, or the like). Planarization may occur via asimultaneous combination of mechanical and chemical etching (e.g.chemical mechanical polishing (CMP)).

“Structural material” as used herein refers to a material that remainspart of the structure when put into use.

“Supplemental structural material” as used herein refers to a materialthat forms part of the structure when the structure is put to use but isnot added as part of the build layers but instead is added to aplurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from a sacrificial material.

“Primary structural material” as used herein is a structural materialthat forms part of a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the structural material volume of the given buildlayer. In some embodiments, the primary structural material may be thesame on each of a plurality of build layers or it may be different ondifferent build layers. In some embodiments, a given primary structuralmaterial may be formed from two or more materials by the alloying ordiffusion of two or more materials to form a single material.

“Secondary structural material” as used herein is a structural materialthat forms part of a given build layer and is typically deposited orapplied during the formation of the given build layer but is not aprimary structural material as it individually accounts for only a smallvolume of the structural material associated with the given layer. Asecondary structural material will account for less than 20% of thevolume of the structural material associated with the given layer. Insome preferred embodiments, each secondary structural material mayaccount for less than 10%, 5%, or even 2% of the volume of thestructural material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary structural materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns). The coatings maybe applied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931, now U.S. Pat. No.7,239,219. In other embodiments, such coatings may be applied in anon-planar manner, for example, in openings in and over a patternedmasking material that has been applied to previously planarized layersof material as taught in U.S. patent application Ser. No. 10/841,383,now U.S. Pat. No. 7,195,989. These referenced applications areincorporated herein by reference as if set forth in full herein.

“Functional structural material” as used herein is a structural materialthat would have been removed as a sacrificial material but for itsactual or effective encapsulation by other structural materials.Effective encapsulation refers, for example, to the inability of anetchant to attack the functional structural material due toinaccessibility that results from a very small area of exposure and/ordue to an elongated or tortuous exposure path. For example, large(10,000 μm²) but thin (e.g. less than 0.5 microns) regions ofsacrificial copper sandwiched between deposits of nickel may defineregions of functional structural material depending on ability of arelease etchant to remove the sandwiched copper.

“Sacrificial material” is material that forms part of a build layer butis not a structural material. Sacrificial material on a given buildlayer is separated from structural material on that build layer afterformation of that build layer is completed and more generally is removedfrom a plurality of layers after completion of the formation of theplurality of layers during a “release” process that removes the bulk ofthe sacrificial material or materials. In general sacrificial materialis located on a build layer during the formation of one, two, or moresubsequent build layers and is thereafter removed in a manner that doesnot lead to a planarized surface. Materials that are applied primarilyfor masking purposes, i.e. to allow subsequent selective deposition oretching of a material, e.g. photoresist that is used in forming a buildlayer but does not form part of the build layer) or that exist as partof a build for less than one or two complete build layer formationcycles are not considered sacrificial materials as the term is usedherein but instead shall be referred as masking materials or astemporary materials. These separation processes are sometimes referredto as a release process and may or may not involve the separation ofstructural material from a build substrate. In many embodiments,sacrificial material within a given build layer is not removed until allbuild layers making up the three-dimensional structure have been formed.Of course sacrificial material may be, and typically is, removed fromabove the upper level of a current build layer during planarizationoperations during the formation of the current build layer. Sacrificialmaterial is typically removed via a chemical etching operation but insome embodiments may be removed via a melting operation orelectrochemical etching operation. In typical structures, the removal ofthe sacrificial material (i.e. release of the structural material fromthe sacrificial material) does not result in planarized surfaces butinstead results in surfaces that are dictated by the boundaries ofstructural materials located on each build layer. Sacrificial materialsare typically distinct from structural materials by having differentproperties therefrom (e.g. chemical etchability, hardness, meltingpoint, etc.) but in some cases, as noted previously, what would havebeen a sacrificial material may become a structural material by itsactual or effective encapsulation by other structural materials.Similarly, structural materials may be used to form sacrificialstructures that are separated from a desired structure during a releaseprocess via the sacrificial structures being only attached tosacrificial material or potentially by dissolution of the sacrificialstructures themselves using a process that is insufficient to reachstructural material that is intended to form part of a desiredstructure. It should be understood that in some embodiments, smallamounts of structural material may be removed, after or during releaseof sacrificial material. Such small amounts of structural material mayhave been inadvertently formed due to imperfections in the fabricationprocess or may result from the proper application of the process but mayresult in features that are less than optimal (e.g. layers with stairssteps in regions where smooth sloped surfaces are desired. In such casesthe volume of structural material removed is typically minusculecompared to the amount that is retained and thus such removal is ignoredwhen labeling materials as sacrificial or structural. Sacrificialmaterials are typically removed by a dissolution process, or the like,that destroys the geometric configuration of the sacrificial material asit existed on the build layers. In many embodiments, the sacrificialmaterial is a conductive material such as a metal. As will be discussedhereafter, masking materials though typically sacrificial in nature arenot termed sacrificial materials herein unless they meet the requireddefinition of sacrificial material.

“Supplemental sacrificial material” as used herein refers to a materialthat does not form part of the structure when the structure is put touse and is not added as part of the build layers but instead is added toa plurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from an initial sacrificial material. This supplementalsacrificial material will remain in place for a period of time and/orduring the performance of certain post layer formation operations, e.g.to protect the structure that was released from a primary sacrificialmaterial, but will be removed prior to putting the structure to use.

“Primary sacrificial material” as used herein is a sacrificial materialthat is located on a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the sacrificial material volume of the given buildlayer. In some embodiments, the primary sacrificial material may be thesame on each of a plurality of build layers or may be different ondifferent build layers. In some embodiments, a given primary sacrificialmaterial may be formed from two or more materials by the alloying ordiffusion of two or more materials to form a single material.

“Secondary sacrificial material” as used herein is a sacrificialmaterial that is located on a given build layer and is typicallydeposited or applied during the formation of the build layer but is nota primary sacrificial materials as it individually accounts for only asmall volume of the sacrificial material associated with the givenlayer. A secondary sacrificial material will account for less than 20%of the volume of the sacrificial material associated with the givenlayer. In some preferred embodiments, each secondary sacrificialmaterial may account for less than 10%, 5%, or even 2% of the volume ofthe sacrificial material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary sacrificial materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns). The coatings maybe applied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931, now U.S. Pat. No.7,239,219. In other embodiments, such coatings may be applied in anon-planar manner, for example, in openings in and over a patternedmasking material that has been applied to previously planarized layersof material as taught in U.S. patent application Ser. No. 10/841,383,now U.S. Pat. No. 7,195,989. These referenced applications areincorporated herein by reference as if set forth in full herein.

“Adhesion layer”, “seed layer”, “barrier layer”, and the like refer tocoatings of material that are thin in comparison to the layer thicknessand thus generally form secondary structural material portions orsacrificial material portions of some layers. Such coatings may beapplied uniformly over a previously formed build layer, they may beapplied over a portion of a previously formed build layer and overpatterned structural or sacrificial material existing on a current (i.e.partially formed) build layer so that a non-planar seed layer results,or they may be selectively applied to only certain locations on apreviously formed build layer. In the event such coatings arenon-selectively applied, selected portions may be removed (1) prior todepositing either a sacrificial material or structural material as partof a current layer or (2) prior to beginning formation of the next layeror they may remain in place through the layer build up process and thenetched away after formation of a plurality of build layers.

“Masking material” is a material that may be used as a tool in theprocess of forming a build layer but does not form part of that buildlayer. Masking material is typically a photopolymer or photoresistmaterial or other material that may be readily patterned. Maskingmaterial is typically a dielectric. Masking material, though typicallysacrificial in nature, is not a sacrificial material as the term is usedherein. Masking material is typically applied to a surface during theformation of a build layer for the purpose of allowing selectivedeposition, etching, or other treatment and is removed either during theprocess of forming that build layer or immediately after the formationof that build layer.

“Multilayer structures” are structures formed from multiple build layersof deposited or applied materials.

“Multilayer three-dimensional (or 3D or 3-D) structures” are MultilayerStructures that meet at least one of two criteria: (1) the structuralmaterial portion of at least two layers of which one has structuralmaterial portions that do not overlap structural material portions ofthe other.

“Complex multilayer three-dimensional (or 3D or 3-D) structures” aremultilayer three-dimensional structures formed from at least threelayers where a line may be defined that hypothetically extendsvertically through at least some portion of the build layers of thestructure will extend from structural material through sacrificialmaterial and back through structural material or will extend fromsacrificial material through structural material and back throughsacrificial material (these might be termed vertically complexmultilayer three-dimensional structures). Alternatively, complexmultilayer three-dimensional structures may be defined as multilayerthree-dimensional structures formed from at least two layers where aline may be defined that hypothetically extends horizontally through atleast some portion of a build layer of the structure that will extendfrom structural material through sacrificial material and back throughstructural material or will extend from sacrificial material throughstructural material and back through sacrificial material (these mightbe termed horizontally complex multilayer three-dimensional structures).Worded another way, in complex multilayer three-dimensional structures,a vertically or horizontally extending hypothetical line will extendfrom one or structural material or void (when the sacrificial materialis removed) to the other of void or structural material and then back tostructural material or void as the line is traversed along at least aportion of the line.

“Moderately complex multilayer three-dimensional (or 3D or 3-D)structures are complex multilayer 3D structures for which thealternating of void and structure or structure and void not only existsalong one of a vertically or horizontally extending line but along linesextending both vertically and horizontally.

“Highly complex multilayer (or 3D or 3-D) structures are complexmultilayer 3D structures for which the structure-to-void-to-structure orvoid-to-structure-to-void alternating occurs once along the line butalso occurs a plurality of times along a definable horizontally orvertically extending line.

“Up-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a next build layer “n+1” that is to beformed from a given material that exists on the build layer “n” but doesnot exist on the immediately succeeding build layer “n+1”. Forconvenience the term “up-facing feature” will apply to such featuresregardless of the build orientation.

“Down-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a preceding build layer “n−1” that is tobe formed from a given material that exists on build layer “n” but doesnot exist on the immediately preceding build layer “n−1”. As withup-facing features, the term “down-facing feature” shall apply to suchfeatures regardless of the actual build orientation.

“Continuing region” is the portion of a given build layer “n” that isdictated by the cross-sectional data for the given build layer “n”, anext build layer “n+1” and a preceding build layer “n−1” that is neitherup-facing nor down-facing for the build layer “n”.

“Minimum feature size” or “MFS” refers to a necessary or desirablespacing between structural material elements on a given layer that areto remain distinct in the final device configuration. If the minimumfeature size is not maintained for structural material elements on agiven layer, the fabrication process may result in structural materialinadvertently bridging what were intended to be two distinct elements(e.g. due to masking material failure or failure to appropriately fillvoids with sacrificial material during formation of the given layer suchthat during formation of a subsequent layer structural materialinadvertently fills the void). More care during fabrication can lead toa reduction in minimum feature size. Alternatively, a willingness toaccept greater losses in productivity (i.e. lower yields) can result ina decrease in the minimum feature size. However, during fabrication fora given set of process parameters, inspection diligence, and yield(successful level of production) a minimum design feature size is set inone way or another. The above described minimum feature size may moreappropriately be termed minimum feature size of gaps or voids (e.g. theMFS for sacrificial material regions when sacrificial material isdeposited first). Conversely a minimum feature size for structurematerial regions (minimum width or length of structural materialelements) may be specified. Depending on the fabrication method andorder of deposition of structural material and sacrificial material, thetwo types of minimum feature sizes may be the same or different. Inpractice, for example, using electrochemical fabrication methods asdescribed herein, the minimum features size on a given layer may beroughly set to a value that approximates the layer thickness used toform the layer and it may be considered the same for both structural andsacrificial material widths. In some more rigorously implementedprocesses (e.g. with higher examination regiments and tolerance forrework), it may be set to an amount that is 80%, 50%, or even 30% of thelayer thickness. Other values or methods of setting minimum featuresizes may be used. Worded another way, depending on the geometry of astructure, or plurality of structures, being formed, the structure, orstructures, may include elements (e.g. solid regions) which havedimensions smaller than a first minimum feature size and/or havespacings, voids, openings, or gaps (e.g. hollow or empty regions)located between elements, where the spacings are smaller than a secondminimum feature size where the first and second minimum feature sizesmay be the same or different and where the minimum feature sizesrepresent lower limits at which formation of elements and/or spacing canbe reliably formed. Reliable formation refers to the ability toaccurately form or produce a given geometry of an element, or of thespacing between elements, using a given formation process, with aminimum acceptable yield. The minimum acceptable yield may depend on anumber of factors including: (1) number of features present per layer,(2) numbers of layers, (3) the criticality of the successful formationof each feature, (4) the number and severity of other factors effectingoverall yield, and (5) the desired or required overall yield for thestructures or devices themselves. In some circumstances, the minimumsize may be determined by a yield requirement per feature which is aslow as 70%, 60%, or even 50%. While in other circumstances the yieldrequirement per feature may be as high as 90%, 95%, 99%, or even higher.In some circumstances (e.g. in producing a filter element) the failureto produce a certain number of desired features (e.g. 20-40% failure maybe acceptable while in an electrostatic actuator the failure to producea single small space between two moveable electrodes may result infailure of the entire device. The MFS, for example, may be defined asthe minimum width of a narrow and processing element (e.g. photoresistelement or sacrificial material element) or structural element (e.g.structural material element) that may be reliably formed (e.g. 90-99.9times out of 100) which is either independent of any wider structures orhas a substantial independent length (e.g. 200-1000 microns) beforeconnecting to a wider region.

“Layerize” or “Layerized” refer to the conversion of a 3D CAD design orother design of a structure into a plurality of layers or cross-sectionsrepresenting the successive layers which define a quantized version ofthe structure as it might be formed. Layerization requires that aparticular layering axis be defined (e.g. X, Y, or Z) and that alayering resolution (i.e. layer thickness) be specified for the variouslevels along the layering axis. The layering resolutions may be fixed orvariable.

Miniature Threaded Elements Formed from Multi-Material Multi-LayerProcesses

Embodiments of the invention provide threaded elements alone, in matingpairs, and/or in conjunction with other elements. Some needs for threadsarise from a desire to assemble micro-scale devices and to attachmicro-scale devices (permanently or temporarily) to other micro-scaledevices or to larger-scale devices. Threads can also be used to providerelative motion of one component with respect to another within a singledevice. Such relative motion may be used to position separate componentsor to bias different portions of a single structure. Such relativemotion may be used to lock component into desired positions or to lockout components from moving into undesired positions (e.g. to ensure thatcomponents move from fabrication positions to functional or operationalpositions and do not move back to fabrication positions). Suchcomponents may also be used to convert rotational motion totranslational motion (e.g. as in an ACME thread, lead screw, or ballscrew arrangement).

Screws or other threaded elements may also be used to preload elementsof a micro-device that are fabricated in one position but which whenmoved to another position can provide a force (e.g., preloading a springto hold a pressure relief valve closed). Screws or other threadedelements (temporary or permanent) may also be used for purposes ofhandling devices.

The multi-layer multi-material fabrication methods as taught hereinenable the fabrication of threads on a scale that is not possiblethrough conventional thread forming techniques. Even when conventionalthread forming techniques are viable, it is advantageous to avoidadditional process steps or assembly steps to form threads or to add athreaded component. At one extreme, a device made using such methods maycomprise ready-to use threads; at the other extreme, a device maycomprise holes which may be threaded using conventional methods (e.g.,taps and dies). Between the two extremes, a device may comprise threadsor partial threads which are produced using the multi-material,multi-layer fabrication methods of the present application but which canundergo additional processing (e.g., via a tap or die) before use. Thelast approach might be used, for example, to reduce the clearancesbetween a male and female threads if fabrication of the entire threadedassembly in an assembled state using the multi-layer, multi-materialmethods set forth herein would produce an undesirably large clearance.In cases when a female thread requires tapping before use, the EFABstructure may incorporate features such as holes and channels tofacilitate release of chips and other fragments produced by the tappingprocess.

FIG. 17 illustrates a sample device 700 having holes 722 that can betapped wherein, the odd-numbered holes starting from the left (seen incross section) are provided with such a channel 724, while theeven-numbered holes are not.

Both female and male threads may be made. In some cases, a threadfabricated using a multi-material, multi-layer electrochemicalfabrication method is required to work with aconventionally-manufactured thread (e.g., an EFAB-produced male threadmay be required to work with a commercially-available fastener orthreaded nut). In the case where the scale of the thread is smaller thanwhat is achievable through conventional manufacturing, both male andfemale threads can be produced using the methods taught herein. Matchingmale and female threads can be fabricated in a fully orpartially-engaged state, or separately (in which case, a reducedclearance between the two threads may be possible).

There are few limitations on the form that a thread can take whenfabricated using a multi-layer multi-material electrochemical process.For instance, in the case of a linear stage, an ACME thread form mightbe required. In the case of a permanent assembly, an interference threadmight be required. The designer may conform to an existing thread formstandard, or use an arbitrary thread form. However, the layer thicknessdoes have a direct impact on the minimum possible thread pitch. In someembodiments it may be preferable to correlate the thread pitch to thelayer thickness or thicknesses that will be used such that the pitchcorresponds to an integral number of layers while in other embodiments,such preference may not exist. In some embodiments, it may be desirableto ensure that the inner and outer diameter of the screw threadscorrespond to integral numbers of layers so that the thread whenlayerized will have as symmetric a configuration as possible. It mayalso be desirable to ensure that the layerization of the thread elementscommences at a desired layerization height relative to the threadpositions so that a controlled and predictable conversion from asmoothed wall design to a layered version occurs. For a very fine pitchthread, a build with at least some thin layers may be useful. Ingeneral, it is desirable to have a layer thickness that is no greaterthan about ⅕ to ⅙ of the thread pitch (i.e. the axial length associatedwith each full revolution, 360°, of the threaded element) and morepreferably no greater than ⅛ the thread pitch or even smaller. In somespecialized embodiments, it may be possible to have fewer layers perthread pitch but special care may be required in designing and/or inlayerizing the female and male portions to ensure that layers are formedwith appropriate configurations. Furthermore as ratio of layers tothread pitch decreases it is more likely that discontinuities in axialmovement will be more apparent as rotation of the thread element orelements occur. In particular, biasing care may be necessary (e.g. viaspring loading and compression or lifting during turning so that thestairsteps in the thread elements can move past one another. In someembodiments, when coupled with appropriate biasing, the stairstepsbetween layers may provide for thread locking which in some cases may bereleased by manually overcoming the biasing force. In some embodimentsadditional elements or features may be formed along with or as part ofthe threaded elements, such additional features may include for example,(1) spring elements that push male and female element away from oneanother, (2) spring elements that compress male and female elementstogether, (3) washers, (4) lock washers, (5) engagement mechanisms, (6)thread heads, (7) engagement notches and protrusions may be incorporatedon the threads of the threaded elements or on other portions of thethreaded elements to provide locking engagement, (8) features forengaging tools via compression such as allen wrenches, screw driverflats, screw driver cross-points, and the like, and/or (9) features forengaging tools via lifting or tensional engagement such as loops orhooks.

In some implementations, particularly when male and female threads maybe formed in an engaged state, it may be advantageous to provide etchingholes or the like in the body of the female element to ensure adequateaccess for etching solution to reach the intervening sacrificialmaterial.

In some embodiments, male elements may be formed with internal passageswhich may or may not be provided female threading for receiving smallermale elements. In some embodiments it may be desirable to provide onlyrighted handed threaded elements while in other embodiments it may beadvantageous to provide only left hand threaded elements while in stillother embodiments a combination of the two may be provided.

Threads may be designed using 3-D CAD as continuous, smooth, spiralingfeatures. During fabrication by multi-material, multi-layer fabricationmethods, these features will take on stair stepped or quantizedconfigurations. In such cases it is generally necessary to modify threaddesigns from more traditional designs so that minimum feature sizeviolations do not occur during the formation of individual layers and/orso that interference issues do not arise between male and femaleelements of close tolerance as a result of layerization processes. Thisis particularly true when the treaded elements will be formed with theirlongitudinal axis different from that of the layer stacking axis thatwill be used during fabrication of the device. In particular suchmodification may involve the need to remove selected regions from thedesign geometry. The regions requiring removal may be ascertained afterlayerizing the design and looking at individual layers of the design tolocate regions where minimum feature size violations exist and thenadding structure or removing structure, whichever is more preferable, toremove the violations and thereafter using the modified design data toform the structure. The resulting threads may have portions missing ortruncated, and may no longer be symmetric. The modifications may beperformed using the original 3-D CAD design, or on a 2-D basis using thelayered version of the CAD design, or using a combination of bothapproaches.

Regions for potential modification include those regions which may bespaced from one another on a single layer by a gap which is smaller thanthe minimum feature size. Such gaps may be found at lower and upperjunctions where adjacent threads join when the threaded element will befabricated with its axial direction perpendicular to the direction oflayer stacking (e.g. in lowest and highest regions of minimum radialdimension for male elements and the lowest and highest regions ofmaximum radial dimension for female elements). If problems exist inthese regions, design modifications where regions of material areremoved (or added) may be appropriate so as to remove the small gaps.Other regions for potential modification include regions where the widthof the structural material may be too thin. Such thin features may befound at the upper and lower extends of the threads when the threadedelement will be fabricated with its axial direction perpendicular to thedirection of layer stacking (e.g. in lowest and highest regions ofmaximum radial dimension for male elements and the lowest and highestregions of minimum radial dimension for female elements).

Additional regions for modification may exist if the male and femalethreads are to be formed in an engaged or partially engaged state wherethe spacing or clearance between the elements is too tight. In suchsituations, the elements may be formed in an unengaged state or bywidening the gap in the engaged regions.

When forming threaded elements with their axial orientation aligned withthe build axis, unexpected interferences may also occur particularlywhen the clearance between the ideal male and female elements is at oronly slightly greater than the minimum feature size and where the threadpitch is not sufficiently large relative to the thicknesses of thefabrication layers. Such interferences may occur as a result of theclearance reductions resulting from quantization or layerizationparticularly when levels do not correspond to minimum radial extends ofmale thread elements (making them somewhat larger in diameter) andmaximum radial extends of female element (making them somewhat smallerin diameter). If such growth is sufficiently large it could poseunintended interference issues as the male and female threads arerotated relative to each other or simply cause minimum feature sizeviolations when formed in an engaged configuration.

In some alternative embodiments of the invention, such minimum featuresize issues and interference issues may be dealt with by an overalldesign modification as opposed to the check and modify approach of someembodiments. The design modification may involve increasing the axialwidths of both the minimum radial features and maximum radial featuresof both the male and female elements such that the axial widths exceedthe minimum feature size requirement (particularly when the build axisand the axial orientation of the thread element are not parallel). Whenthe build axis and the axial orientation of the thread element areparallel it may be desirable to ensure that the layer thickness andthread pitch are selected so that they do not result in radial offsetsover the height of a single layer that approach the designed clearancebetween the male and female thread elements and/or to ensure that theradial minimums and maximums on the male and female features do notinterfere by ensuring they are formed with desired radial dimensions byproviding them with an axial width or length greater than one layerthickness. FIG. 18 provides a cut view of an example male and femalethreaded element where both elements have similar axial lengths fortheir minimum and maximum radial dimensions wherein the elements havecertain radial thread overlap that is dictated by the thread pitch andthe required axial length of the minimum and maximum features. FIG. 19provides a cut view of an alternative configuration where the minimumand maximum radial features for the male thread have similar axiallengths while the minimum and maximum radial features for the femalethread also have similar axial lengths but which are about half thelength of that of the their male counterparts.

In some other alternative embodiments, it may be possible to use maleand female thread designs where improved mating and clearance can beachieved by configuring the maximum radial dimensions of the maleelement to have relatively small axial lengths while the minimum radialdimensions of the male element have larger axial lengths conversely theminimum radial dimensions of the female element may have small axialwidths and/or reduced radial dimensions (allowing them to fitcomfortably into the axially lengthened minimum dimensions of the maleelement) and the maximum radial dimensions of the female element may beaxially lengthened. An example of such a configuration is shown in thecut view of FIG. 20 showing a male threaded element threaded into afemale element where axial lengths of minimum and maximum radialextensions are not the same.

Because of the design flexibility afforded by the multi-layer,multi-material electrochemical fabrication process, threads of unusualgeometry may be produced in addition to standard left and right-handedthreads, whether of constant diameter or tapered. Examples includehollow screws or threads; cork-screws or threads without central coreelements, screws or threads with curved or straight channels,semi-flexible screws or threaded elements, threads with variable crosssectional diameters, screws or threads with varying pitch, segmentedthreads or screws, threads or screws with built-in features such ascoaxial helical springs, leaf springs (e.g., for use in preloading),washers, lock washers, and the like.

In some embodiments, as an alternative to fabricating threads onstructural elements produced by multi-material, multi-layer process EFABstructures, threads can be provided by incorporating existing screws,studs, nuts, threaded rods, and the like into such structures. Forexample, a male thread in the form of a stud may be provided by buildinga structure with a hole into which a stud is inserted and secured byadhesive, welding, press-fitting, shrink fitting, by capturing the headof a screw in a specially-designed cavity such that the screw shaftprotrudes, or (if the hole has built-in threads) by screwing it intoplace. Cavities or structures able to receive a nut or other femalethreaded component may also be provided. In some embodiments, structuresintended to receive threaded components may be equipped with catches orother spring-like features to retain the components.

Various features of the above noted embodiments are further describedbelow with the aid of the illustrations of FIGS. 5A-20.

FIG. 5A-5C provide plan (FIG. 5A), perspective (FIG. 5B), andperspective section (FIG. 5C) views of a solid model of a male threadedstructure or element without modifications that address minimum featuresize limitations or other interference issues as may be necessary whenforming the device from a plurality of adhered layers. The threadedstructure 100 has a longitudinal or axial orientation as shown by arrow103 and perpendicular radial directions as shown by arrow 105. This malethreaded element has regions of minimal radial extension 112 with radialextents labeled as MR_(min) and regions of maximum radial extension 102labeled as MR_(max).

FIGS. 6A-6F provide plan views (FIGS. 6B-6D), perspective views (FIG.6A), and perspective section views (FIGS. 6E-6F) of a solid model of amale threaded structure or element 200 having an axial orientation 203along the Y-axis and design modifications 204 and 214 on portions of themaximum radial features 202 and minimum radial features 212,respectively, to allow formation without violating minimum feature sizerules. These modifications, down trimmings, or flattening of the maximumand minimum radial features have been provided at the tops and bottomsof these features relative to an assumed layerization or layer stackingthat may occur along the Z-axis as illustrated in FIGS. 6B and 6C. FIG.6D labels the actual radial dimensions of the minimum and maximumfeatures with an MR_(min) and an MR_(max) respectively while FIG. 6Bshows the radial dimensions of the trimmed minimum and maximum featureswith MR_(min-T) and MR_(max-T) respectively. The differences betweentrimmed extents and untrimmed extents is defined as the differencebetween MR_(min) and MR_(min-T) and MR_(max) and MR_(max-T) respectivelywhile the axial width expansions associated with the radial decreases isthe difference between axial lengths of the untrimmed and trimmedfeatures (not labeled).

FIGS. 7A-7C provide a perspective view (FIG. 7A), plan section views(FIGS. 7B & 7D), and perspective section views (FIGS. 7C-7D) views of asolid model of a sample female threaded structure or element 250configured to mate with male threaded element 200 of FIGS. 6A-6F whereinthe design modifications, trimmings, or flattenings 264 on the minimumradial features 262 allow formation without violating minimum featuresize rules. The threaded structure 250 has a longitudinal or axialorientation shown by line 253 and XYZ orientations as shown by thevarious axes. Radial dimensions of the minimum and maximum radialextents are labeled IN FIG. 7D as FR_(min) and FR_(max) respectively.Portions of the minimum radial features associated with the femalethreads are shown as being expanded (i.e. axially widened) by thetrimming or flattening of regions 264. In some embodiments, as shown inFIGS. 7A and 7D, the female element may include passages 270 that extendfrom the inward facing threaded regions to a region external to theelement. Such passages may be useful in a release process that separatesthe structural material of the elements from sacrificial material afterlayer formation is complete.

FIGS. 8A-8B provide a mated or partially engaged perspective sectionview (FIG. 8B) and a mated or partially engaged perspective view (FIG.8A) view of the male and female threaded structures or elements of FIGS.6A-7E.

FIGS. 9A & 9B provide a perspective view (FIG. 9A) and a perspectivesection view (FIG. 9B) of a layerized male threaded structure or element300 with the stacking axis of the layers being parallel to thelongitudinal axis 303 of the threaded device wherein the threaded deviceincludes spiraling regions of maximum radial extension 302 and minimumradial extension 312 at each position along the axial length of thethreaded element.

FIGS. 10A & 10B provide a perspective view (FIG. 10A) and perspectivesection view (FIG. 10B) of a layerized male threaded structure orelement 400 with the stacking axis 407 of the layers being perpendicularto the longitudinal axis 403 of the threaded structure wherein theillustrated structure shows trimmed regions 414 and 404 relative toregions 402 and 412 of minimum and maximum radial extents. The trimmedregions 414 and 404 may exist on the lowest and highest layers of theminimum and maximum radial extents and may include minimum and maximumradial extents as these are the locations that are most like to sufferfrom minimum feature size violations. In some embodiments however, otherlayer stacking orientations relative to the trimmed regions arepossible.

FIGS. 11A & 11B provide a perspective view (FIG. 11A) and perspectivesection view of a layerized female threaded structure or element 350with the stacking direction of the layers corresponding to thelongitudinal axis 353 of the threaded device wherein release holes 370can be seen in the side of FIG. 11A.

FIGS. 12A & 12B provide a perspective view (FIG. 12A) and a perspectivesection view (FIG. 12B) of a layerized female threaded structure orelement with the stacking direction 457 of the layers beingperpendicular to the longitudinal axis 453 of the threaded devicewherein etching holes 470 can be seen extending from the threaded regionof the section view of FIG. 12B to the upper and lower surfaces of thestructure.

FIGS. 13A-13C a provide plan view (FIG. 13A), a perspective view (FIG.13B), and section view (FIG. 13C) of a solid model of a male threadedstructure or element having design modifications that allow formationwithout violating minimum feature size rules, wherein the designmodifications include expanded axial lengths (i.e. flattened or trimmedradial extents) of both the maximum and minimum radially extendingportions (as indicated by lengths 504 and 514 respectively) of thethreaded element. Unlike the limited or selective flattening or trimmingof FIGS. 6A-6F, the flattening or trimming of FIGS. 13A-13C extendaround the entire radial sprial and axial length of the maximum andminimum radial extensions. FIG. 13A also shows axis of the threadedelement with line 503 and shows that the minimum axial extents andtrimmed minimum axial extents are equal as are the maximum axial extentsand the trimmed maximum axial extents. In some preferred embodiments,the axial widths resulting from the trimming are at least as great asthe layer thickness or are at least as large as the minimum featuresize. In other embodiments, other axial widths are possible and may bedifferent for the minimum and maximum radial elements.

FIGS. 14A-14B provide a perspective (FIG. 14A) and perspective sectionview (FIG. 14B) of a solid model of a female threaded structure 550 orelement having the design modifications corresponding to those of malethreaded structure of FIGS. 13A and 13B (as indicated by lengths 504 and514 respectively). In some embodiments, the width of the maximum radialfemale thread extensions may be equal to or somewhat smaller than thatof their male counterparts while the width of the minimum female radialextensions may be equal to or somewhat greater than that of their malecounterparts. In some embodiments, the spacing between male and femalethread regions may be relative uniform while in other embodiments thegaps may vary between minimum extents, sloping regions, and maximumextents.

FIG. 15A-15C provide a plan view (FIG. 15A), a perspective view (FIG.15B), and a perspective section view (FIG. 15C) of a solid model of amale threaded structure 600 that comes closer to a cork-screw or helicalconfiguration of the device as whole as opposed to only the threadsedges themselves tracing a helical path. The device of FIGS. 15A-15C hassimilar design modifications as compared to those set forth in FIGS.13A-13C (as indicated by lengths 604 and 614 respectively). As notedabove, such design modifications may result in structure or deviceformation while avoiding violation of minimum feature size rules.

Depending on the maximum radial extents of the threaded element and across-sectional width of the solid helical element the minimal radialextents may define either an outward facing surface relative to thedevice axis (positive radius as in FIGS. 5A-5C, 6A-6F, 9A-9C, and10A-10B) yielding a non-helical or non-cork screw configuration or aninward facing surface relative to the device axis thereby yielding atrue helical, cork screw, or coreless configuration of the threadedstructure as a whole.

FIG. 15D provides a layerized version of the threaded device 600 ofFIGS. 15A-15C with a stacking axis 607 perpendicular to the longitudinalaxis 603 of the thread element.

FIGS. 16A and 16B provide a perspective view (FIG. 16A) and aperspective section view (FIG. 16B) of a solid model 650 of a femalemale threaded structure or element corresponding to the male element ofFIGS. 15A-15C. This structure includes flattened or trimmed edges alongthe entire lengths of both the minimum and maximum radial features asindicated by lengths 654 and 664 respectively which, as noted above, maybe useful in allowing layered formation of the structure withoutviolating minimum feature size rules. Passages 670 are also shown asexisting in the structure and may be used as release passages orpossibly as removal passages for interfering material that is removedprior to putting the structure into actual use or that is removed as aresult of actual use.

FIG. 17 illustrates a sample device 700 having holes 721-724 that can betapped wherein the odd-numbered holes 721 and 723 (seen in crosssection) are provided with channels 725, while the even-numbered holesare not. These channels may facilitate release of chips and otherfragments produced by the tapping process.

FIG. 18 provides a cut view of example male and female threaded elements800 and 850, having common axes 803 and 853 where both elements havesimilar axial lengths for their minimum and maximum radial dimensionswherein the elements have certain radial thread overlap 820 that isdictated by, for example, the thread pitch and the required axial lengthof the minimum and maximum features. As shown, maximum radial extents814R and 864R have matching axial extents 814L and 864L, minimum radialextents 804R and 854R have matching axial extents 804L and 854L.

FIG. 19 provides a cut view of an alternative thread configuration of amale threaded element 900 and a female threaded element 950 that havecommon axes 903 and 953, and a thread overlap of 920 where the minimumand maximum radial features for the male thread have similar axiallengths, 904L to 914L while the minimum and maximum radial features forthe female thread also have similar axial lengths, 954L to 964L, butwhere the axial lengths of the female features are only about one-halfof that of the male features.

FIG. 20 provides a cut view of an alternative thread configuration of amale threaded element 1000 and a female threaded element 1050, that havecommon axes 1003 and 1053, and a thread overlap of 1020 where theminimum and maximum radial features for the male thread have differentaxial lengths, 1004L to 1014L while the minimum and maximum radialfeatures for the female thread also have different axial lengths, 1054Lto 1064L, but where the axial lengths 1054L of the minimum radial femalefeatures 1054R are less than that 1004L of the minimum radial malefeatures 1004R and the maximum radial length 1064L of the maximum femaleradial features 1064R are greater than that 1014L of the maximum radialmale features 1014R. In still other embodiments, different combinationsof maximum radial extends, maximum axial lengths, minimum radialextents, and minimum radial lengths are possible.

Numerous variations of the above noted embodiments are possibleincluding, for example: (1) different thread pitches (axial length per360° revolution), (2) instead of continuous threads, the threads may bediscontinuous in nature on one or both the male and female elements, (3)different ratios of maximum and minimum radial extents, (4) differenttypes of sloped sidewalls connecting maximum and minimum radial extentsto one another, (5) different angles on sloped side walls, (6) differentlevels of extension of male and female thread elements, (7) use ofthread elements with multiple parallel threads as opposed to the singlethreads illustrated, (8) different axial lengths of threads on male andfemale elements, (9) female threaded receptacles having male centersinto and around which male cork screws elements can thread, (9) threadedelements that include compliant elements for enhanced retention orenhanced centering of male and female elements, (10) threaded elementsthat have varying pitch at some axial position to cause interference forenhanced retention, (11) threaded elements without expanded heads.

As noted above in some embodiment, potential interference and minimumfeature size issues may be resolved by the selective removal ofpotential conflicting regions or by the global modification of thedesign features. In some embodiments, modifications may be limited to amale element or a female element while in other embodiments themodifications may be made to both.

In some alternative embodiments, the threaded elements may be formed bymulti-layer multi-materials fabrication methods but instead of buildingup the structure from a plurality of planar layers the structure may beformed from a plurality of cylindrical or other layer configurations.Such formation methods are described in U.S. Pat. No. 6,027,630,referenced above, and in U.S. Patent Application No. 61/141,797, filedDec. 31, 2008, by Cohen and entitled “Cylindrical Multi-Layer,Multi-Material Electrochemical Fabrication Methods” and U.S. patentapplication Ser. No. 12/651,088 (Microfabrica Docket No. P-US281-A-SC),filed Dec. 31, 2009 by Cohen and entitled “Cylindrical Multi-Layer,Multi-Material Electrochemical Fabrication Methods”. These patents andapplications are incorporated herein by reference as if set forth infull herein.

In some embodiments, the threaded devices may have tapering diameter inwhich the maximum and/or minimum radial extents may have differentmagnitudes at different axial positions along the length of the threadedelement. The thread elements may include heads with tool engagementsurfaces or tool engagement surfaces may be formed directly into one orboth ends of a threaded structure. The threads of threaded structuresmay be axially continuous or discontinuous. The threaded structures mayhave only a fractional portion of a complete 360° turn or may includemultiple complete turns (e.g. two to ten turns). Portions of the threadelement may include clips, springs, varied pitch, varied diameter, orother retention enhancing features. Planar layer stacking in fabricationmethods and in formed devices may have an axis that is parallel,perpendicular, or at some other angle relative to the axis of thethreaded element. In some embodiments, thread formation may be completefrom the layer fabrication process while in other embodiments, threadingor threading enhancement may occur in supplemental processing steps suchas taping or die cutting.

Further Comments and Conclusions

Structural or sacrificial dielectric materials may be incorporated intoembodiments of the present invention in a variety of different ways.Such materials may form a third material or higher deposited on selectedlayers or may form one of the first two materials deposited on somelayers. Additional teachings concerning the formation of structures ondielectric substrates and/or the formation of structures thatincorporate dielectric materials into the formation process andpossibility into the final structures as formed are set forth in anumber of patent applications filed Dec. 31, 2003. The first of thesefilings is U.S. Patent Application No. 60/534,184 which is entitled“Electrochemical Fabrication Methods Incorporating Dielectric Materialsand/or Using Dielectric Substrates”. The second of these filings is U.S.Patent Application No. 60/533,932, which is entitled “ElectrochemicalFabrication Methods Using Dielectric Substrates”. The third of thesefilings is U.S. Patent Application No. 60/534,157, which is entitled“Electrochemical Fabrication Methods Incorporating DielectricMaterials”. The fourth of these filings is U.S. Patent Application No.60/533,891, which is entitled “Methods for Electrochemically FabricatingStructures Incorporating Dielectric Sheets and/or Seed layers That ArePartially Removed Via Planarization”. A fifth such filing is U.S. PatentApplication No. 60/533,895, which is entitled “ElectrochemicalFabrication Method for Producing Multi-layer Three-DimensionalStructures on a Porous Dielectric”. Additional patent filings thatprovide teachings concerning incorporation of dielectrics into the EFABprocess include U.S. patent application Ser. No. 11/139,262, filed May26, 2005 by Lockard, et al., and which is entitled “Methods forElectrochemically Fabricating Structures Using Adhered Masks,Incorporating Dielectric Sheets, and/or Seed Layers that are PartiallyRemoved Via Planarization”; and U.S. patent application Ser. No.11/029,216, filed Jan. 3, 2005 by Cohen, et al., now abandoned, andwhich is entitled “Electrochemical Fabrication Methods IncorporatingDielectric Materials and/or Using Dielectric Substrates”. These patentfilings are each hereby incorporated herein by reference as if set forthin full herein.

Some embodiments may employ diffusion bonding or the like to enhanceadhesion between successive layers of material. Various teachingsconcerning the use of diffusion bonding in electrochemical fabricationprocesses are set forth in U.S. patent application Ser. No. 10/841,384which was filed May 7, 2004 by Cohen et al., now abandoned, which isentitled “Method of Electrochemically Fabricating Multilayer StructuresHaving Improved Interlayer Adhesion” and which is hereby incorporatedherein by reference as if set forth in full. This application is herebyincorporated herein by reference as if set forth in full.

Some embodiments may incorporate elements taught in conjunction withother medical devices as set forth in various U.S. patent applicationsfiled by the owner of the present application and/or may benefit fromcombined use with these other medical devices: Some of these alternativedevices have been described in the following previously filed patentapplications: (1) U.S. patent application Ser. No. 11/478,934, by Cohenet al., and entitled “Electrochemical Fabrication ProcessesIncorporating Non-Platable Materials and/or Metals that are Difficult toPlate On”; (2) U.S. patent application Ser. No. 11/582,049, by Cohen,and entitled “Discrete or Continuous Tissue Capture Device and Methodfor Making”; (3) U.S. patent application Ser. No. 11/625,807, by Cohen,and entitled “Microdevices for Tissue Approximation and Retention,Methods for Using, and Methods for Making”; (4) U.S. patent applicationSer. No. 11/696,722, by Cohen, and entitled “Biopsy Devices, Methods forUsing, and Methods for Making”; (5) U.S. patent application Ser. No.11/734,273, by Cohen, and entitled “Thrombectomy Devices and Methods forMaking”; (6) U.S. Patent Application No. 60/942,200, by Cohen, andentitled “Micro-Umbrella Devices for Use in Medical Applications andMethods for Making Such Devices”; and (7) U.S. patent application Ser.No. 11/444,999, by Cohen, and entitled “Microtools and Methods forFabricating Such Tools”. Each of these applications is incorporatedherein by reference as if set forth in full herein.

Though the embodiments explicitly set forth herein have consideredmulti-material layers to be formed one after another. In someembodiments, it is possible to form structures on a layer-by-layer basisbut to deviate from a strict planar layer on planar layer build upprocess in favor of a process that interlaces material between thelayers. Such alternative build processes are disclosed in U.S.application Ser. No. 10/434,519, filed on May 7, 2003, now U.S. Pat. No.7,252,861, entitled Methods of and Apparatus for ElectrochemicallyFabricating Structures Via Interlaced Layers or Via Selective Etchingand Filling of Voids. The techniques disclosed in this referencedapplication may be combined with the techniques and alternatives setforth explicitly herein to derive additional alternative embodiments. Inparticular, the structural features are still defined on aplanar-layer-by-planar-layer basis but material associated with somelayers is formed along with material for other layers such thatinterlacing of deposited material occurs. Such interlacing may lead toreduced structural distortion during formation or improved interlayeradhesion. This patent application is herein incorporated by reference asif set forth in full.

The patent applications and patents set forth below are herebyincorporated by reference herein as if set forth in full. The teachingsin these incorporated applications can be combined with the teachings ofthe instant application in many ways: For example, enhanced methods ofproducing structures may be derived from some combinations of teachings,enhanced structures may be obtainable, enhanced apparatus may bederived, and the like.

US Pat App No., Filing Date US App Pub No., Pub Date US Patent No., PubDate Inventor, Title 09/493,496 - Jan. 28, 2000 Cohen, “Method ForElectrochemical Fabrication” PAT 6,790,377 - Sep. 14, 2004 10/677,556 -Oct. 1, 2003 Cohen, “Monolithic Structures Including Alignment and/or2004 - 0134772 - Jul. 15, 2004 Retention Fixtures for AcceptingComponents” 10/830,262 - Apr. 21, 2004 Cohen, “Methods of ReducingInterlayer Discontinuities 2004 - 0251142A - Dec. 16, 2004 inElectrochemically Fabricated Three-Dimensional PAT 7,198,704 - Apr. 3,2007 Structures” 10/271,574 - Oct. 15, 2002 Cohen, “Methods of andApparatus for Making High 2003 - 0127336A - Jul. 10, 2003 Aspect RatioMicroelectromechanical Structures” PAT 7,288,178 - Oct. 30, 200710/697,597 - Dec. 20, 2002 Lockard, “EFAB Methods and ApparatusIncluding Spray 2004 - 0146650A - Jul. 29, 2004 Metal or Powder CoatingProcesses” 10/677,498 - Oct. 1, 2003 Cohen, “Multi-cell Masks andMethods and Apparatus for 2004 - 0134788 - Jul. 15, 2004 Using SuchMasks To Form Three-Dimensional PAT 7,235,166 - Jun. 26, 2007Structures” 10/724,513 - Nov. 26, 2003 Cohen, “Non-Conformable Masks andMethods and 2004 - 0147124 - Jul. 29, 2004 Apparatus for FormingThree-Dimensional Structures” PAT 7,368,044 - May 6, 2008 10/607,931 -Jun. 27, 2003 Brown, “Miniature RF and Microwave Components and 2004 -0140862 - Jul. 22, 2004 Methods for Fabricating Such Components” PAT7,239,219 - Jul. 3, 2007 10/841,100 - May 7, 2004 Cohen,“Electrochemical Fabrication Methods Including 2005 - 0032362 - Feb. 10,2005 Use of Surface Treatments to Reduce Overplating and/or PAT7,109,118 - Sep. 19, 2006 Planarization During Formation of Multi-layerThree- Dimensional Structures” 10/387,958 - Mar. 13, 2003 Cohen,“Electrochemical Fabrication Method and 2003 - 022168A - Dec. 4, 2003Application for Producing Three-Dimensional Structures Having ImprovedSurface Finish” 10/434,494 - May 7, 2003 Zhang, “Methods and Apparatusfor Monitoring 2004 - 0000489A - Jan. 1, 2004 Deposition Quality DuringConformable Contact Mask Plating Operations” 10/434,289 - May 7, 2003Zhang, “Conformable Contact Masking Methods and 2004 - 0065555A - Apr.8, 2004 Apparatus Utilizing In Situ Cathodic Activation of a Substrate”10/434,294 - May 7, 2003 Zhang, “Electrochemical Fabrication MethodsWith 2004 - 0065550A - Apr. 8, 2004 Enhanced Post Deposition Processing”10/434,295 - May 7, 2003 Cohen, “Method of and Apparatus for FormingThree- 2004 - 0004001A - Jan. 8, 2004 Dimensional Structures IntegralWith Semiconductor Based Circuitry” 10/434,315 - May 7, 2003 Bang,“Methods of and Apparatus for Molding Structures 2003 - 0234179 A - Dec.25, 2003 Using Sacrificial Metal Patterns” PAT 7,229,542 - Jun. 12, 200710/434,103 - May 7, 2004 Cohen, “Electrochemically FabricatedHermetically 2004 - 0020782A - Feb. 5, 2004 Sealed Microstructures andMethods of and Apparatus PAT 7,160,429 - Jan. 9, 2007 for Producing SuchStructures” 10/841,006 - May 7, 2004 Thompson, “ElectrochemicallyFabricated Structures 2005 - 0067292 - May 31, 2005 Having Dielectric orActive Bases and Methods of and Apparatus for Producing Such Structures”10/434,519 - May 7, 2003 Smalley, “Methods of and Apparatus for 2004 -0007470A - Jan. 15, 2004 Electrochemically Fabricating Structures ViaInterlaced PAT 7,252,861 - Aug. 7, 2007 Layers or Via Selective Etchingand Filling of Voids” 10/724,515 - Nov. 26, 2003 Cohen, “Method forElectrochemically Forming Structures 2004 - 0182716 - Sep. 23, 2004Including Non-Parallel Mating of Contact Masks and APT 7,291,254 - Nov.6, 2007 Substrates” 10/841,347 - May 7, 2004 Cohen, “Multi-step ReleaseMethod for Electrochemically 2005 - 0072681 - Apr. 7, 2005 FabricatedStructures” 60/533,947 - Dec. 31, 2003 Kumar, “Probe Arrays and Methodfor Making” 60/534,183 - Dec. 31, 2003 Cohen, “Method and Apparatus forMaintaining Parallelism of Layers and/or Achieving Desired Thicknessesof Layers During the Electrochemical Fabrication of Structures”11/733,195 - Apr. 9, 2007 Kumar, “Methods of Forming Three-Dimensional2008 - 0050524 - Feb. 28, 2008 Structures Having Reduced Stress and/orCurvature” 11/506,586 - Aug. 8, 2006 Cohen, “Mesoscale and MicroscaleDevice Fabrication 20007 - 0039828 - Feb. 22, 2007 Methods Using SplitStructures and Alignment Elements” 10/949,744 - Sep. 24, 2004 Lockard,“Three-Dimensional Structures Having Feature 2005 - 0126916 - Jun. 16,2005 Sizes Smaller Than a Minimum Feature Size and Methods forFabricating”

Though various portions of this specification have been provided withheaders, it is not intended that the headers be used to limit theapplication of teachings found in one portion of the specification fromapplying to other portions of the specification. For example, it shouldbe understood that alternatives acknowledged in association with oneembodiment, are intended to apply to all embodiments to the extent thatthe features of the different embodiments make such applicationfunctional and do not otherwise contradict or remove all benefits of theadopted embodiment. Various other embodiments of the present inventionexist. Some of these embodiments may be based on a combination of theteachings herein with various teachings incorporated herein byreference.

In view of the teachings herein, many further embodiments, alternativesin design and uses of the embodiments of the instant invention will beapparent to those of skill in the art. As such, it is not intended thatthe invention be limited to the particular illustrative embodiments,alternatives, and uses described above but instead that it be solelylimited by the claims presented hereafter.

We claim:
 1. A micro-scale or millimeter scale male threaded element, comprising (a) an axial dimension and a radial dimension that extends perpendicular to the axial dimension; (b) at least one outward facing thread comprising radial extensions and radial depressions that define a spiral turn of at least 90° around and along the axial dimension; wherein the threaded element has a stair stepped configuration with the stair steps defining a plurality of planes spaced from adjacent planes by a layer thickness, wherein there exists a maximum and minimum radial extension for the thread for each axial position; and wherein selected portions of the radial features of the threaded element meet a criteria selected from the group consisting of: (1) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions, (2) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as the layer thickness, (3) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as a minimum feature size, (4) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the minimum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions, (5) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the minimum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as the layer thickness, and (6) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the minimum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as a minimum feature size.
 2. The element of claim 1 wherein the spiral turn is continuous.
 3. The element of claim 1 wherein the spiral turn is discontinuous.
 4. The element of claim 1 wherein the spiral turn extends at least 180°.
 5. The element of claim 1 wherein the spiral turn extends at least 360°.
 6. The element of claim 1 wherein the spiral turn extends at least 720°.
 7. The element of claim 1 wherein the male threaded element is configured to thread into a counterpart female threaded element.
 8. A micro-scale or millimeter scale female threaded element, comprising: (a) an axial dimension and a radial dimension that extends perpendicular to the axial dimension; (b) at least one inward facing thread comprising radial extensions defining openings of smaller radius and radial depressions defining openings of larger radius, wherein the thread provides a spiral turn of at least 90° around and along the axial dimension; wherein the thread has a stair stepped configuration with the stair steps defining a plurality of planes spaced from adjacent planes by a layer thickness, wherein there exists a maximum and minimum radial extension for the thread for each axial position; and wherein selected portions of the radial features of the threaded element meet a criteria selected from the group consisting of: (1) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions, (2) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as the layer thickness, (3) the selected portions are located along the maximum radial dimension and are flattened relative to non-selected portions of the maximum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as a minimum feature size, (4) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the axial length of the non-selected portions, (5) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the minimum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as the layer thickness, and (6) the selected portions are located along the minimum radial dimension along and are flattened relative to non-selected portions of the minimum radial dimension such that the selected portions have longer axial lengths relative to the axial length of the non-selected portions wherein the longer axial length is at least as large as a minimum feature size.
 9. The element of claim 8 wherein the spiral turn is continuous.
 10. The element of claim 8 wherein the spiral turn is discontinuous.
 11. The element of claim 8 wherein the spiral turn extends at least 180°.
 12. The element of claim 8 wherein the spiral turn extends at least 360°.
 13. The element of claim 8 wherein the spiral turn extends at least 720°.
 14. The element of claim 8 wherein the female threaded element is configured to receive a counterpart male threaded element.
 15. A micro-scale or millimeter scale device, comprising: (a) a male threaded element, comprising: i. an axial dimension and a radial dimension that extends perpendicular to the axial dimension; ii. at least one outward facing thread comprising radial extensions and radial depressions that define a spiral turn of at least 90° around and along the axial dimension; wherein the male threaded element has a stair stepped configuration with the stair steps defining a plurality of planes spaced from adjacent planes by a layer thickness, and (b) a female threaded element, comprising: i. an axial dimension and a radial dimension that extends perpendicular to the axial dimension; ii. at least one inward facing female thread comprising radial extensions defining openings of smaller radius and radial depressions defining openings of larger radius, wherein the thread provides a spiral turn of at least 90° around and along the axial dimension; wherein the female threaded element has a stair stepped configuration with the stair steps defining a plurality of planes spaced from adjacent planes by a layer thickness, wherein the male threaded element is configured to thread into the female threaded element.
 16. The device of claim 15 wherein the spiral turn of the male threaded element is continuous.
 17. The device of claim 16 wherein the spiral turn of the female threaded element is continuous.
 18. The device of claim 16 wherein the spiral turn of the female threaded element is discontinuous.
 19. The device of claim 15 wherein the spiral turn of the male threaded element is discontinuous.
 20. The device of claim 19 wherein the spiral turn of the female threaded element is continuous.
 21. The device of claim 19 wherein the spiral turn of the female threaded element is discontinuous.
 22. The device of claim 15 wherein the spiral turn of both the male and female threaded elements extends at least 180°.
 23. The device of claim 15 wherein the spiral turn of both the male and female threaded elements extends at least 360°.
 24. The device of claim 15 wherein the spiral turn of both the male and female threaded elements extends at least 720°.
 25. The device of claim 15 wherein the female threaded element includes a plurality of release holes.
 26. The device of claim 15 wherein the male threaded element comprises a coreless thread.
 27. The device of claim 15 wherein the male threaded element comprises a helix without a central core.
 28. The device of claim 15 wherein the male threaded element comprises a multiple threaded element. 